[ { "id": "https://authors.library.caltech.edu/records/9xzcg-7h151", "eprint_id": 120479, "eprint_status": "archive", "datestamp": "2023-08-20 08:58:34", "lastmod": "2023-10-23 15:31:19", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tumuklu-Ozgur", "name": { "family": "Tumuklu", "given": "Ozgur" }, "orcid": "0000-0002-0990-2583" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" }, { "id": "Hanquist-Kyle-M", "name": { "family": "Hanquist", "given": "Kyle M." }, "orcid": "0000-0002-3817-8942" } ] }, "title": "Development of a hybrid particle-continuum solver for studying plume expansion into rarefied flows", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2023 by California Institute of Technology.", "abstract": "The direct simulation Monte Carlo (DSMC) method and unsteady Navier-Stokes (NS) are combined in a hybrid formulation with an ultimate aim to model positioning-rocket lam- inar jet expansion in the lunar atmosphere. The hybrid solver uses the Schwarz technique, a classical matching procedure of the length scales and time scales between the continuum and rarefied environments. The novelty of the current work is its ability to be applied to unsteady problems and to accommodate a large variation in Knudsen number (Kn) values. The length scale coupling from the continuum to the DSMC region is determined by a criterion based on the local gradient-length of Kn, which according to the specified criterion is larger than the continuum breakdown parameter set at the value of 0.05 at the transi- tion from continuum to rarefied conditions for a jet. To this end, one-dimensional steady shock configurations with upstream Mach numbers varying between 1.7 to 8.4 are studied. Perfect agreement is achieved with measurements, indicating that spatial coupling between the rarefied and continuum regions is performed precisely. To ensure time accuracy in the coupling, the number of DSMC time steps is determined by the ratio of the continuum (i.e., NS) time step to the DSMC time step, which is governed by the mean collision time of particles. A relatively good agreement between the measurement data and current work for unsteady shock motion indicates that the hybrid framework can model time-dependent flows accurately.", "date": "2023-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2023-0073", "id_number": "CaltechAUTHORS:20230327-902951000.33", "isbn": "978-1-62410-699-6", "book_title": "AIAA SCITECH 2023 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230327-902951000.33", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2023-0073", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2023-0073", "resource_type": "book_section", "pub_year": "2023", "author_list": "Tumuklu, Ozgur; Bellan, Josette R.; et el." }, { "id": "https://authors.library.caltech.edu/records/w63ma-va045", "eprint_id": 113396, "eprint_status": "archive", "datestamp": "2023-08-20 06:29:00", "lastmod": "2023-10-23 15:35:17", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tumuklu-Ozgur", "name": { "family": "Tumuklu", "given": "Ozgur" }, "orcid": "0000-0002-0990-2583" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Development and validation studies of a multi-purpose DSMC code", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2022 by Jet Propulsion Laboratory, California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "A parallel direct simulation Monte Carlo (DSMC) solver has been developed to ultimately couple with an existing granular code in order to model positioning-rocket plume expansion in the lunar atmosphere and its interaction with the regolith. The challenge is to develop of a multi-species DSMC efficient model and code to fit the target problem. This model and code are here described and results from the model are compared for validation and verification purposes either with existing experimental data or with similar results from similar simulations of wall-bounded canonical flows. In particular, the modeling of Couette flow with different collision schemes provides an opportunity to select a sufficiently numerically efficient collision model to reduce computational costs. Since the objective of the code is to study expansion flows including the plume species of CO\u2082, N\u2082, and H\u2082O and their interactions with the multi-species composition of the Moon atmosphere (i.e. Ar, He, and Ne), thermal and mass diffusion of mixtures were also studied to show that the code accurately models multispecies situations. To acquire such an ability, the collision and sampling algorithm of the single species code was improved to handle complex multi-species gas interactions. A good agreement with experimental data is achieved, showing that the code accurately predicts the thermal and mass diffusion coefficients of mixtures. Finally, the expanding nature of the plume results in thermochemical nonequilibrium flow, especially in rarefied environments, due to insufficient collision rates. To this end, the rate and the amount of energy transfer among the translational, rotational, and vibrational modes are tested with the previous numerical data and with analytical results.", "date": "2022-01-03", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2022-2017", "id_number": "CaltechAUTHORS:20220210-928459000", "isbn": "978-1-62410-631-6", "book_title": "AIAA SCITECH 2022 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220210-928459000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2022-2017", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2022-2017", "resource_type": "book_section", "pub_year": "2022", "author_list": "Tumuklu, Ozgur and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/k9th9-xgh93", "eprint_id": 113381, "eprint_status": "archive", "datestamp": "2023-08-20 06:28:11", "lastmod": "2023-10-23 15:34:34", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharan-Nek", "name": { "family": "Sharan", "given": "Nek" }, "orcid": "0000-0002-7274-8232" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "High-pressure two-species mixing in turbulent free jets", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2022 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "Engine performance and exhaust gas composition in numerous automotive/aerospace propulsion systems depends on the fuel-oxidizer mixing at high pressures. A fundamental understanding of the high-pressure (p) flow dynamics is hence key to improving the engine efficiency. Turbulent round jet direct numerical simulations are performed in this study at a Reynolds number (based on jet diameter and jet-exit velocity) of 5000 to understand binary-species mixing in supercritical conditions. For comparison, single-species flows at atmospheric as well as supercritical pressure are also investigated. The effects of species-concentration gradients on thermal and mass diffusion are significant in a binary-species flow. Moreover, large density (or thermodynamic) fluctuations can occur because of the differences in injected and chamber fluid density/temperature resulting in noticeable Soret effects. The paper discusses preliminary results from an investigation eventually aimed at examining multicomponent species injection and mixing.", "date": "2022-01-03", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2022-0482", "id_number": "CaltechAUTHORS:20220210-928340000", "isbn": "978-1-62410-631-6", "book_title": "AIAA SCITECH 2022 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220210-928340000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2022-0482", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2022-0482", "resource_type": "book_section", "pub_year": "2022", "author_list": "Sharan, Nek and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/crhvs-4nw22", "eprint_id": 113388, "eprint_status": "archive", "datestamp": "2023-08-20 06:28:34", "lastmod": "2023-10-23 15:35:00", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Toki-Takahiko", "name": { "family": "Toki", "given": "Takahiko" }, "orcid": "0000-0002-3408-0681" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Influence of the Soret effect on binary-species boundary layers at high pressure", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2022 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "Direct numerical simulations of binary-species temporal boundary layers at high pressure are performed. The main objective is to investigate the influence of the Soret effect on flow physics of binary-species boundary layers where the fluid has a uniform composition. The working fluid is a mixture of 25 % methane and 75 % nitrogen in mass fraction. Although the fluid composition is uniform at the initial condition, the mass fraction of methane increases near the wall when the wall temperature is hotter than the free stream temperature, whereas it decreases when the wall temperature is colder. The non-uniform mass fraction indicates that the uphill diffusion occurs near the wall. Investigation of fluctuations of the mass fraction reveals that the mass fraction fluctuates in the whole boundary layer, indicating that the uphill diffusion occurs even far from the wall. Examination of the species-mass diffusion balance for mean flow fields clarified that the Soret effect flux becomes large near the wall, and the large flux causes the non-uniform profile of the mass fraction near the wall.", "date": "2022-01-03", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2022-1368", "id_number": "CaltechAUTHORS:20220210-928401000", "isbn": "978-1-62410-631-6", "book_title": "AIAA SCITECH 2022 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220210-928401000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2022-1368", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2022-1368", "resource_type": "book_section", "pub_year": "2022", "author_list": "Toki, Takahiko and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/bqyrr-dsn91", "eprint_id": 107432, "eprint_status": "archive", "datestamp": "2023-08-20 01:22:53", "lastmod": "2023-10-23 15:53:25", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Balakrishnan-Kaushik", "name": { "family": "Balakrishnan", "given": "Kaushik" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Cratering in a Granular Bed due to an Impinging Supersonic Jet Penetrating a Planetary Atmosphere in the Continuum Regime", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2021 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "High-fidelity three-dimensional numerical simulations are analyzed to investigate cratering on a granular bed of particles due to a supersonic multi-species fluid jet. In the simulations, the volume-averaged two-phase equations are solved with a multi-species Large-Eddy Simulation formulation for the fluid and a Kinetic-Theory-based model for the particle bed. The simulations vary according to the ratio of the jet-to-ambient fluid density (and pressure) and the jet density. The characteristics of the jets and crater are examined and they are found to be different according to the cross-sectional shape which is determined by the jet/ambient density ratio: a conical shape is observed when the ratio is close to unity, and a parabolic shape occurs when this ratio is large. The variation of the crater diameter time-wise evolution is evaluated, and the time-wise evolution of the ratio between the upper or lower crater depths and the crater diameter are also examined. The azimuthally averaged ejecta radial variation is inspected, and joint probability density functions elucidate the regions where gravity effects are important, and the Mach number regime in different parts of the flow.", "date": "2021-01-11", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2021-0752", "id_number": "CaltechAUTHORS:20210112-105611902", "isbn": "9781624106095", "book_title": "AIAA Scitech 2021 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210112-105611902", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2021-0752", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2021-0752", "resource_type": "book_section", "pub_year": "2021", "author_list": "Balakrishnan, Kaushik and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/41hz5-a9953", "eprint_id": 107434, "eprint_status": "archive", "datestamp": "2023-08-20 01:23:00", "lastmod": "2023-10-23 15:53:32", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharan-Nek", "name": { "family": "Sharan", "given": "Nek" }, "orcid": "0000-0002-7274-8232" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Direct numerical simulation of high-pressure free jets", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2021 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "Understanding turbulent round-jet flow dynamics at supercritical pressures is crucial to controlling fuel-oxidizer mixing and combustion in numerous propulsion systems. To that end, direct numerical simulations (DNS) of round jets are performed to discern the differences between turbulence and mixing characteristics at atmospheric and supercritical conditions. Single-species isothermal jets, with Nitrogen (N\u2082) injected into N\u2082 at same temperature, are considered at Reynolds number (Re_{D}), based on jet diameter (D) and jet-exit velocity (U_e), of 5000. To understand mixing characteristics, a passive scalar with unity Schmidt number is transported with the flow. For supercritical conditions, the compressible flow equations with the Peng-Robinson equation of state are solved to examine the influence of thermodynamic compressibility, quantified by the compressibility factor (Z), on jet-flow dynamics. The results show that decreasing Z at a fixed supercritical ambient pressure (p_\u221e) enhances the pressure and density fluctuations (non-dimensionalized by the local mean pressure and density, respectively), but the effect on velocity fluctuations depends also on local flow dynamics characterized by mean strain rates.", "date": "2021-01-11", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2021-0550", "id_number": "CaltechAUTHORS:20210112-105612042", "isbn": "9781624106095", "book_title": "AIAA Scitech 2021 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210112-105612042", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2021-0550", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2021-0550", "resource_type": "book_section", "pub_year": "2021", "author_list": "Sharan, Nek and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/9nv2h-vk631", "eprint_id": 107433, "eprint_status": "archive", "datestamp": "2023-08-20 01:22:56", "lastmod": "2023-10-23 15:53:29", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Toki-Takahiko", "name": { "family": "Toki", "given": "Takahiko" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Direct numerical simulation of single-species and binary-species boundary layers at high pressure", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2021 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "Direct numerical simulations of single-species and binary-species temporal boundary layers at high pressure are performed. The main objective is to investigate flow physics in a binary-species boundary layer at high pressure, with special attention to mass diffusion. The working fluids are nitrogen in the single-species cases, and a mixture of nitrogen and methane in the binary-species cases. An investigation of mean profiles shows that velocity and temperature profiles have steep gradients near the wall, whereas the mass fraction profiles do not have a steep gradient. This result indicates that the similarity law between velocity, temperature and mass fraction does not hold true in the binary-species boundary layer. The comparison of turbulent fluctuations shows that the qualitative characteristics of velocity and temperature are similar to each other. In contrast, profiles of mass fraction fluctuations are largely different from those of velocity and temperature. This result indicates that mass diffusion is not similar to momentum and thermal diffusions in binary-species boundary layers.", "date": "2021-01-11", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2021-0682", "id_number": "CaltechAUTHORS:20210112-105611979", "isbn": "9781624106095", "book_title": "AIAA Scitech 2021 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210112-105611979", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2021-0682", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2021-0682", "resource_type": "book_section", "pub_year": "2021", "author_list": "Toki, Takahiko and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/ar2r8-yss41", "eprint_id": 100661, "eprint_status": "archive", "datestamp": "2023-08-19 19:29:49", "lastmod": "2023-10-18 21:43:39", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Banuti-D-T", "name": { "family": "Banuti", "given": "Daniel" }, "orcid": "0000-0002-5469-5704" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Inter-species molecular attraction effect in the development of a two-species mixing layer", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2020 American Institute of Aeronautics and Astronautics. \n\nPublished Online: 5 Jan 2020.", "abstract": "Simulations of fluid mixing occurring at high-pressures mandate the use of real-fluid equations of state to capture the effect of both intermolecular repulsive forces and attractive forces which are neglected in perfect gases. Dedicated mixing rules account for these forces by providing a generic mapping of the mixture state-space onto a pure fluid domain. However, the specific inter-species molecular forces depend on the particular characteristics of the molecular pairs under consideration, and typically require the knowledge of binary interaction coefficients k\u03b1\u03b2 . The impact of k\u03b1\u03b2 on a flow field is as of now unclear; further, k\u03b1\u03b2 is unknown for many molecular pairs and when unknown, set to be null. This study addresses the impact of k\u03b1\u03b2 on the temporal evolution of a real-fluid mixing layer and uses Direct Numerical Simulation (DNS) to explore this impact. The results show differences between augmented attraction (k\u03b1\u03b2 < 0) and diminished attraction (k\u03b1\u03b2 > 0), affecting both fluid dynamics and diffusion processes. Specifically, in a binary mixing layer, it is observed that augmented attraction leads to delayed transition and mixing layer growth, manifested in the momentum layer thickness. The fractal dimension as a measure of interface corrugation likewise shows a delayed development for augmented attraction. These results provide an hitherto undocumented mechanism affecting the development of mixing layers.", "date": "2020-01-05", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2020-1155", "id_number": "CaltechAUTHORS:20200113-083112418", "isbn": "978-1-62410-595-1", "book_title": "AIAA Scitech 2020 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200113-083112418", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2020-1155", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2020-1155", "resource_type": "book_section", "pub_year": "2020", "author_list": "Banuti, Daniel and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/jvtwf-7vz94", "eprint_id": 100660, "eprint_status": "archive", "datestamp": "2023-08-19 19:29:45", "lastmod": "2023-10-18 21:43:36", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bushe-W-K", "name": { "family": "Bushe", "given": "W. Kendal" } }, { "id": "Devaud-C", "name": { "family": "Devaud", "given": "Cecile" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Turbulent high-pressure reaction-rate modeling using the Double-conditioned Conditional Source-term Estimation method", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2020 American Institute of Aeronautics and Astronautics. \n\nPublished Online: 5 Jan 2020.", "abstract": "An evaluation of the submodels constituting the Double-Conditioned Source-term Estimation (DCSE) method for utilization in Large Eddy Simulation (LES) is presented which makes use of a single realization of a turbulent high-pressure reactive-flow database obtained from Direct Numerical Simulation (DNS). A filtered and coarsened DNS (FCDNS) field is first created to mimic a real LES field, and the FCDNS values for thermodynamic variables (temperature, density and species mass fractions) are used as inputs to the DCSE model to predict the FCDNS reaction rates. It is found that there are significant errors in the predictions of the filtered reaction rate compared to the template. These errors are attributed to important aspects of the model, some of which are discussed here, namely, the integral inversion necessary to find the conditional-filtered values of the thermodynamic variables and the modelling of the joint probability density function of the conditioning variables, the latter being by far the largest source of error. Assuming a \u03b2-PDF for the marginal PDF of the reaction progress variable is shown to be a particularly poor choice, as is the assumption that the conditioning variables are statistically independent.", "date": "2020-01-05", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2020-1153", "id_number": "CaltechAUTHORS:20200113-082728582", "isbn": "978-1-62410-595-1", "book_title": "AIAA Scitech 2020 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200113-082728582", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2020-1153", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2020-1153", "resource_type": "book_section", "pub_year": "2020", "author_list": "Bushe, W. Kendal; Devaud, Cecile; et el." }, { "id": "https://authors.library.caltech.edu/records/vv6kj-wfj33", "eprint_id": 100662, "eprint_status": "archive", "datestamp": "2023-08-19 19:29:52", "lastmod": "2023-10-18 21:43:42", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharan-N", "name": { "family": "Sharan", "given": "Nek" }, "orcid": "0000-0002-7274-8232" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Turbulent mixing in supercritical jets: effect of compressibility factor and inflow condition", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2020 American Institute of Aeronautics and Astronautics. \n\nPublished Online: 5 Jan 2020.", "abstract": "Fuel injection and turbulent mixing at supercritical pressures determines ignition and combustion in numerous engineering applications. Flow evolution under such conditions is characterized by strong non-linear coupling between dynamics, transport coefficients, and thermodynamics. Experimental studies observe that the jets injected at supercritical pressures exhibit significantly different dynamics from the jets at subcritical conditions, owing to the lack of distinct liquid and gas phases in supercritical state. Thus, the averaged flow quantities such as the potential core length, jet spatial growth rate and velocity decay profiles differ in the two conditions, resulting in different mixed-fluid distributions. In this study, turbulent jet direct numerical simulations (DNS) are performed to examine the variations in flow statistics between injection of Nitrogen (N\u2082) in Nitrogen (N\u2082) at both subcritical (perfect-gas) and supercritical conditions. In all cases, isothermal round jets at Reynolds number (Re_{D}), based on jet diameter (D) and jet orifice velocity (U\u2080), of 5000 are considered. For mixing analyses, a passive scalar transported with the flow is examined.", "date": "2020-01-05", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2020-1156", "id_number": "CaltechAUTHORS:20200113-083457410", "isbn": "978-1-62410-595-1", "book_title": "AIAA Scitech 2020 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200113-083457410", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2020-1156", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2020-1156", "resource_type": "book_section", "pub_year": "2020", "author_list": "Sharan, Nek and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/hf6qz-f9b53", "eprint_id": 97650, "eprint_status": "archive", "datestamp": "2023-08-19 13:48:43", "lastmod": "2023-10-18 16:10:46", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Devaud-C", "name": { "family": "Devaud", "given": "Cecile" } }, { "id": "Bushe-W-K", "name": { "family": "Bushe", "given": "W. Kendal" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Modeling of the Turbulent Reaction Rate in High-Pressure Flows", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2019 American Institute of Aeronautics and Astronautics.", "abstract": "The modeling of turbulence-chemistry-thermodynamic interaction is addressed through an a priori study pf a Direct Numerical Simulation (DNS) database representing high-p turbulent combustion. The DNS database consists of simulations of a temporal mixing layer in which a single-step chemical reaction occurs; the results are presented here for a single DNS realization. The potential of the single-conditioned Conditional Source-term Estimate (CSE) approach to model the filtered turbulent reaction rate needed for conducting Large Eddy Simulation (LES) is examined. Evaluations conducted with the mixture fraction as a conditioning variable at two filter widths and with the probability distribution function (PDF) extracted from the DNS database representing the mixture fraction, show that the deviation between the model and template is large and substantially increases with filter width. To address this deviation, the Double-conditioned Source-term Estimate (DCSE) approach is explored with two different second conditioning variables, the first conditioning variable being still the mixture fraction; several filter widths are considered. The first choice of the second conditioning variable is a normalized process variable based on the CO_2 mass fraction and the second choice of the second conditioning variable is a normalized temperature. With each second conditional variable, the DCSE results represent a substantial improvement over CSE, by as much as an order of magnitude when measured by the relative error from the filtered reaction rate. A quantitative test based on a root mean square identifies the reason for the DCSE success compared to CSE, the DCSE is able to reduce the departure of the fluctuations of the modeled reaction rate from the filtered reaction rate over the entire range of the filtered reaction rate values. Comparing the DCSE results obtained with the two second conditioning variables, it appears that the normalized process variable based on the CO_2 mass fraction as the second conditioning variable is more successful than the normalized temperature in modeling the filtered reaction rate over its entire range.", "date": "2019-01-07", "date_type": "published", "publisher": "AIAA", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2019-1493", "id_number": "CaltechAUTHORS:20190805-134838226", "isbn": "9781624105784", "book_title": "AIAA Scitech 2019 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-134838226", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2019-1493", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2019-1493", "resource_type": "book_section", "pub_year": "2019", "author_list": "Devaud, Cecile; Bushe, W. Kendal; et el." }, { "id": "https://authors.library.caltech.edu/records/trt7c-sq469", "eprint_id": 97646, "eprint_status": "archive", "datestamp": "2023-08-19 13:48:30", "lastmod": "2023-10-18 16:10:33", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharan-N", "name": { "family": "Sharan", "given": "Nek" }, "orcid": "0000-0002-7274-8232" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Numerical aspects for physically accurate Direct Numerical Simulations of turbulent jets", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2019 American Institute of Aeronautics and Astronautics.", "abstract": "Numerical simulations of turbulent isothermal round jets are performed at Reynolds number (based on jet diameter and jet orifice velocity) of 5000 and Mach number of 0.6 to assess influences of initial perturbation, numerical characterization, and boundary treatments on turbulence statistics. The aper documents preliminary results from an investigation eventually aimed at examining multicomponent species injection and mixing at high-pressure conditions relevant to combustion in diesel, gas-turbine and liquid-rocket engines. Lack of reliable experimental or computational results at high pressures of interest make code validation at those conditions infeasible. Therefore, single-species simulations at perfect-gas conditions are first performed to assess turbulence statistics sensitivity to numerical setup. Two cases with different inflow velocity perturbation amplitude are considered to examine influences on jet flow transition and self-similarity.", "date": "2019-01-07", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2019-2011", "id_number": "CaltechAUTHORS:20190805-134837606", "isbn": "9781624105784", "book_title": "AIAA Scitech 2019 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-134837606", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2019-2011", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2019-2011", "resource_type": "book_section", "pub_year": "2019", "author_list": "Sharan, Nek and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/vjs29-bwf45", "eprint_id": 97970, "eprint_status": "archive", "datestamp": "2023-08-19 07:20:18", "lastmod": "2023-10-18 16:55:38", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sciacovelli-L", "name": { "family": "Sciacovelli", "given": "Luca" }, "orcid": "0000-0002-2463-4193" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Mixing in high-pressure flows: the influence of the number of species", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2018 American Institute of Aeronautics and Astronautics.", "abstract": "Mixing of several species in high-pressure (high-p) turbulent flows is investigated to understand the influence of the number of species on the flow characteristics. Direct Numerical Simulations are conducted in the temporal mixing layer configuration at approximately same value of the momentum ratio for all realizations. The simulations are performed with two, three, five and seven species for various compositions, and two values of the free-stream pressure, p_0, which is supercritical for each species. The extensive database thus obtained allows the study of the influence of the composition, p_0, and the initial density ratio. The species effective Schmidt number is computed and it is found that negative values occur for all secondary species - particularly for H_2 - thus indicating uphill diffusion, while the primary species only experience regular diffusion. The probability density function (p.d.f.) of the species-specific effective Schmidt number shows strong variation with p_0 but weak dependence on the number of species; however, the p.d.f. substantially varies with the identity of the species. In contrast, the p.d.f. of the effective Prandtl number indicates dependence on both p_0 and the number of species. Similar to the species-specific effective Schmidt number, the species-specific effective Lewis number p.d.f. depends on the species and for all species the mean is smaller than unity, thus invalidating one of the most popular assumptions in combustion modeling.", "date": "2018-01-08", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2018-1189", "id_number": "CaltechAUTHORS:20190816-144340914", "isbn": "9781624105241", "book_title": "2018 AIAA Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-144340914", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2018-1189", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2018-1189", "resource_type": "book_section", "pub_year": "2018", "author_list": "Sciacovelli, Luca and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/ncpbv-ygw44", "eprint_id": 97964, "eprint_status": "archive", "datestamp": "2023-08-19 07:20:14", "lastmod": "2023-10-18 16:55:10", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Castiglioni-G", "name": { "family": "Castiglioni", "given": "Giacomo" }, "orcid": "0000-0003-0278-6951" }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "The Thermodynamic Regime During Mixing under High-Pressure Conditions", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2018 American Institute of Aeronautics and Astronautics.", "abstract": "Injection and mixing of high-pressure multi-species mixtures are critical processes for several practical systems used in automotive and aerospace industries. Examples include diesel engines, gas turbines, and liquid rocket engines; in all of these devices the pressure of either the fuel or the oxidizer is above critical pressure. To control combustion in the chambers of these engines, one must control the processes of fuel penetration, mixing of reactants and the timing of ignition. The actual control very much depends on the thermodynamic regime of the mixture. Thus, in this study we inquire about the thermodynamic regime of complex mixtures injected in combustion chambers and use the spinodal locus as discriminant to distinguish between single-phase and two-phase regimes. A mathematical formalism is used to first compute spinodal locus for mixtures for which either experimental data or previous computations are available. and it is shown that there is good agreement between the results of the present calculations and that previously existing information. Further, the methodology for computing the spinodal locus is here applied to surrogate diesel fuels. According to these calculations, diesel fuel surrogates are always in the single-phase regime at injection-conditions pressures and temperatures existing in diesel engine combustion chambers.", "date": "2018-01-08", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2018-1188", "id_number": "CaltechAUTHORS:20190816-144340352", "isbn": "9781624105241", "book_title": "2018 AIAA Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-144340352", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2018-1188", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2018-1188", "resource_type": "book_section", "pub_year": "2018", "author_list": "Castiglioni, Giacomo and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/dypde-m6y28", "eprint_id": 82734, "eprint_status": "archive", "datestamp": "2023-08-19 00:54:24", "lastmod": "2023-10-17 22:38:34", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gnanaskandan-A", "name": { "family": "Gnanaskandan", "given": "Aswin" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette R." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Large Eddy Simulations of high pressure jets: Effect of subgrid scale modeling", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2017 American Institute of Aeronautics and Astronautics.", "abstract": "The focus of this study is on developing high-fidelity models and simulations for fully turbulent high-pressure flows. To this end, two Large Eddy Simulation (LES) models are considered and simulations are conducted with these models for initial conditions for which experimental data is available. In the first LES, denoted as Standard LES (SLES), the only subgrid-scale (SGS) model used is that stemming from the convective terms of the conservation equations. In the second LES, a complementary SGS model for the difference between the gradient of the filtered pressure and the gradient of the pressure computed as a function of the filtered flow field is used in the momentum equation additional to the SGS model employed in SLES; this second model is labeled PLES. The comparison of the SLES results with experimental data is favorable, however, PLES visibly enhances the accuracy of the results compared to the same data. A detailed analysis reveals that in PLES the dense-fluid core persists further downstream than in SLES, unsteadiness is increased, and mixing is enhanced further downstream. The differences between PLES and SLES occur in a narrow radial ring of radius three jet diameters around the jet, although they persist at large distances downstream from the inflow. It is recommended that details experimental data should be obtained in this elongated ring region in order to more completely evaluate the potential of PLES compared to SLES.", "date": "2017-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Washington, DC", "pagerange": "2017-1105", "id_number": "CaltechAUTHORS:20171027-125119267", "isbn": "978-1-62410-447-3", "book_title": "55th AIAA Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171027-125119267", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2017-1105", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2017-1105", "resource_type": "book_section", "pub_year": "2017", "author_list": "Gnanaskandan, Aswin and Bellan, Josette R." }, { "id": "https://authors.library.caltech.edu/records/4zh9a-zg007", "eprint_id": 98939, "eprint_status": "archive", "datestamp": "2023-08-20 09:51:55", "lastmod": "2023-10-18 17:44:47", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kourdis-P-D", "name": { "family": "Kourdis", "given": "Panayotis D." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Reduced-species mechanisms for the combustion of cyclohexane using the Local Self Similarity Tabulation method", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2016 American Institute of Aeronautics and Astronautics.", "abstract": "We utilize the Local Self Similarity Tabulation (LS2T) method to drastically downsize the number of species involved in a detailed kinetics mechanism of cyclohexane. Reduced-species mechanisms of 20 and 15 species are constructed out of the 1081 species involved in the detailed kinetics one. Their performance is compared to that of the detailed kinetics one for a lean (\u03c6=0.5), stoichiometric (\u03c6=1.0), and rich (\u03c6=2.0) cyclohexane/air fresh mixture at an initial temperature of 900 K and initial pressures of 20 and 40 bar.", "date": "2016-01-04", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2016-0180", "id_number": "CaltechAUTHORS:20190930-110458633", "isbn": "9781624103933", "book_title": "54th AIAA Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190930-110458633", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2016-0180", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2016-0180", "resource_type": "book_section", "pub_year": "2016", "author_list": "Kourdis, Panayotis D. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/a0e2c-hsg93", "eprint_id": 98279, "eprint_status": "archive", "datestamp": "2023-08-20 09:51:24", "lastmod": "2023-10-18 17:12:52", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Mixture Fraction for High-Pressure Turbulent Reactive Flows", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2016 American Institute of Aeronautics and Astronautics. \n\nPublished Online: 2 Jan 2016.", "abstract": "A database of Direct Numerical Simulations (DNS) representing the mixing of five species under high-pressure (high-p) conditions, and showing the achievement of turbulent conditions, ignition and combustion, has been created for the purpose of understanding the modeling requirements for the turbulent reaction rate under these conditions. Since in a preliminary study it has been established that the primary flame region is of diffusion type, the focus of the study was on the typical scalar used in advanced turbulent reaction rate models for non-premixed atmospheric-p flames: the mixture fraction. Analysis of the database shows that the mixture fraction is not a conserved scalar, contradicting the basic assumption of the atmospheric-p turbulent reaction-rate models. Moreover, even when using the exact moments extracted from the DNS, it is shown that the probability density function (PDF) of the mixture fraction cannot be represented by a \u03b2 PDF. Based on these facts, it appears that new strategies are required for the modeling of the turbulent reaction rate in high-p reacting flows.", "date": "2016-01-02", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2016-1686", "id_number": "CaltechAUTHORS:20190828-075434872", "isbn": "978-1-62410-393-3", "book_title": "54th AIAA Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-075434872", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2016-1686", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2016-1686", "resource_type": "book_section", "pub_year": "2016", "author_list": "Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/dag14-qec60", "eprint_id": 97977, "eprint_status": "archive", "datestamp": "2023-08-20 04:32:26", "lastmod": "2023-10-18 16:55:56", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kourdis-P-D", "name": { "family": "Kourdis", "given": "Panagiotis D." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" }, { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth" } } ] }, "title": "Towards direct simulations of counterflow flames with consistent differential-algebraic boundary conditions", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2015 American Institute of Aeronautics and Astronautics. \n\nThis work was performed at the California Institute of Technology and the Jet Propulsion Laboratory Division of the California Institute of Technology, and was sponsored by United States Army Research Office, with Dr. Ralph Anthenien as contract monitor. Supercomputing time from the DoD HPCMP Open Research Systems and JPL/NASA is gratefully acknowledged.\n\n
Accepted Version - DTIC_ADA625948.pdf
", "abstract": "A new approach for the formulation of boundary conditions for the counterflow configuration is presented. Upon discretization of the steady-state Navier-Stokes equations at the inflow boundaries, numerically algebraic equations are imposed as boundary conditions, while upon discretization of the unsteady Navier-Stokes equations at the outflow, differential boundaries result. It is demonstrated that the resulting numerical differential-algebraic boundary conditions are suitable to account for the multi-directional character of the flow at the boundaries of the counterflow configuration.", "date": "2015-01-05", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2015-1383", "id_number": "CaltechAUTHORS:20190816-144341538", "isbn": "9781624103438", "book_title": "AIAA SciTech : 53rd AIAA Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190816-144341538", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "NASA/JPL/Caltech" } ] }, "other_numbering_system": { "items": [ { "id": "ADA625948", "name": "DTIC" } ] }, "doi": "10.2514/6.2015-1383", "primary_object": { "basename": "DTIC_ADA625948.pdf", "url": "https://authors.library.caltech.edu/records/dag14-qec60/files/DTIC_ADA625948.pdf" }, "resource_type": "book_section", "pub_year": "2015", "author_list": "Kourdis, Panagiotis D.; Bellan, Josette; et el." }, { "id": "https://authors.library.caltech.edu/records/1t7av-bwc94", "eprint_id": 98319, "eprint_status": "archive", "datestamp": "2023-08-20 04:31:18", "lastmod": "2023-10-18 17:15:13", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Borghesi-G", "name": { "family": "Borghesi", "given": "Giulio" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "A priori and a posteriori analyses of multi-species turbulent mixing layers at supercritical-p conditions", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2015 American Institute of Aeronautics and Astronautics. \n\nPublished Online: 3 Jan 2015.", "abstract": "A database of Direct Numerical Simulations (DNS) representing mixing of species under supercritical pressure (supercritical-p) conditions has been created for the purpose of understanding the modelling of \u2207p(\u03a6), \u2207\u00b7q (\u03a6) and \u2207\u2022j\u03b1(\u03a6) in the context of Large Eddy Simulation (LES). The analysis consists of two separate parts. The activities of all terms appearing in the LES equations are first evaluated, and the dominant terms for each of the transport equations are identified. These data are used to check whether the standard LES assumptions \u2207p(\u03a6), = \u2207p(\u03a6), \u2207\u00b7q (\u03a6) = \u2207\u2022j\u03b1(\u03a6) and \u2207\u2022j\u03b1(\u03a6) = \u2207\u2022j\u03b1(\u03a6), which are routinely used for atmospheric-p flows, continue to be valid also in the realm of supercritical-p conditions. Having found that these assumptions do not hold under supercritical-p conditions, alternative modelling strategies for these terms are proposed, and their accuracy with respect to the standard LES assumptions is assessed through a priori and a posteriori analyses.", "date": "2015-01-03", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2015-0162", "id_number": "CaltechAUTHORS:20190828-140923275", "isbn": "978-1-62410-343-8", "book_title": "53rd AIAA Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-140923275", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2015-0162", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2015-0162", "resource_type": "book_section", "pub_year": "2015", "author_list": "Borghesi, Giulio and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/0gwhe-4d922", "eprint_id": 98009, "eprint_status": "archive", "datestamp": "2023-08-19 23:04:53", "lastmod": "2023-10-18 16:57:26", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kourdis-P-D", "name": { "family": "Kourdis", "given": "Panagiotis D." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" }, { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth" } } ] }, "title": "Dimensionality Reduction Using a Dominant Dynamic Variable, Self Similarity and Data Tabulation: Application to Hydrocarbon Oxidation", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2014 American Institute of Aeronautics and Astronautics.\n\nPublished Online: 10 Jan 2014.", "abstract": "A dimensionality reduction method is developed for autonomous dynamical systems exploiting the local (near) self similarity due to the presence of a dominant dynamic variable. The method is coupled with a simple tabulation scheme to take advantage of the computationally more efficient local partial self similarity. The proposed methodology is used to construct reduced kinetics models of hydrocarbon oxidation and is tested for a n-dodecane/air mixture.", "date": "2014-01-10", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2014-0819", "id_number": "CaltechAUTHORS:20190819-150530040", "isbn": "978-1-62410-256-1", "book_title": "52nd Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190819-150530040", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2014-0819", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2014-0819", "resource_type": "book_section", "pub_year": "2014", "author_list": "Kourdis, Panagiotis D.; Bellan, Josette; et el." }, { "id": "https://authors.library.caltech.edu/records/z7hzf-vww38", "eprint_id": 98011, "eprint_status": "archive", "datestamp": "2023-08-19 23:04:57", "lastmod": "2023-10-18 16:57:33", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Borghesi-G", "name": { "family": "Borghesi", "given": "G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Models for the LES equations to describe multi-species mixing occurring at supercritical pressure", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2014 American Institute of Aeronautics and Astronautics. \n\nPublished Online: 10 Jan 2014.", "abstract": "An existing database of Direct Numerical Simulations (DNS) representing mixing of species under supercritical pressure (supercritical-p) conditions has been investigated for the purpose of understanding the modelling of \u2207p(\u03a6), \u2207\u00b7q(\u03a6) and \u2207\u00b7j_o(\u03a6) in the context of Large Eddy Simulation (LES). The analysis consists of two separate parts. The activities of all terms appearing in the LES equations are first evaluated, and the dominant terms for each of the transport equations are identified. These data are used to check whether the standard LES assumptions \u2207p(\u03a6) = \u2207p(\u03a6), \u2207\u00b7q(\u03a6) = \u2207\u00b7q(\u03a6) and \u2207\u00b7j_o(\u03a6) = \u2207\u00b7j_o(\u03a6) which are routinely used for atmospheric-p flows, continue to be valid also in the realm of supercritical-p conditions. Having found that these assumptions do not hold under supercritical-p conditions, alternative modelling strategies for these terms are proposed, and their accuracy with respect to the standard LES assumptions is assessed.", "date": "2014-01-10", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2014-0823", "id_number": "CaltechAUTHORS:20190819-154932580", "isbn": "978-1-62410-256-1", "book_title": "52nd Aerospace Sciences Meeting", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190819-154932580", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2014-0823", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2014-0823", "resource_type": "book_section", "pub_year": "2014", "author_list": "Borghesi, G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/ze2ws-2gd52", "eprint_id": 98207, "eprint_status": "archive", "datestamp": "2023-08-19 14:18:57", "lastmod": "2023-10-18 17:09:10", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Modeling of Steady High-Pressure Laminar Premixed Flames of n-Heptane and Iso-Octane", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2013 American Institute of Aeronautics and Astronautics.", "abstract": "A model is proposed for quasi-one-dimensional steady flame development in the configuration of an inviscid, premixed fuel jet injected into air. The governing equations are written within the framework of a reduced kinetic model based on constituents and species. The reduced kinetic model, previously exercised in a constant-pressure perfectlystirred reactor mode, has been successful at predicting ignition and combustion product and temperature evolution for n-heptane, iso-octane, PRF fuel combinations, and mixtures of iso-octane with either n-pentane or iso-hexane. The differential governing equations are coupled with a real gas equation of state. The flame development model accounts for a full diffusion matrix, and thermal conductivity computed for the species mixture. Results are presented for both n-heptane and iso-octane at stoichiometric conditions over the pressure range of 1 - 40 bar. Additionally, an equivalence ratio study is conducted for iso-octane at a pressure of 40 bar.", "date": "2013-01-07", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2013-1168", "id_number": "CaltechAUTHORS:20190826-092411436", "isbn": "9781624101816", "book_title": "51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190826-092411436", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2013-1168", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2013-1168", "resource_type": "book_section", "pub_year": "2013", "author_list": "Harstad, Kenneth G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/esqwj-88k62", "eprint_id": 98211, "eprint_status": "archive", "datestamp": "2023-08-19 14:19:15", "lastmod": "2023-10-18 17:09:21", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Masi-E", "name": { "family": "Masi", "given": "Enrica" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" }, { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth" } } ] }, "title": "Pressure Effects from Direct Numerical Simulation of High-Pressure Multispecies Mixing", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2013 by the California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "The focus of this study is the understanding of effects of pressure increase or Reynolds number increase in supercritical-pressure flows. To this effect, Direct Numerical Simulations are conducted for supercritical-pressure flows in which five species undergo mixing. The computation of multispecies mixing is based on a full mass-diffusion matrix, a full thermal-diffusion-factor matrix necessary to include Soret and Dufour effects, and both viscosity and thermal conductivity computed for the species mixture. The scaling of the physical viscosity, necessary for conducting DNS, induces a scaling of the other transport properties that respects the accurate values of the Schmidt (Sc) numbers and of the Prandtl (Pr) number. Computations are performed in the configuration of a temporal mixing layer and the results are analyzed to reveal the separate effect of pressure or Reynolds number increase on the flow. The analysis consists of examining vortical aspects of the flow, the fluxes and relevant thermodynamic properties. It is found that a larger pressure has an opposite effect to a larger Reynolds number, mainly by increasing the fluid density and making it more difficult to entrain and mix.", "date": "2013-01-07", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2013-0711", "id_number": "CaltechAUTHORS:20190826-092411849", "isbn": "9781624101816", "book_title": "51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190826-092411849", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2013-0711", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2013-711", "resource_type": "book_section", "pub_year": "2013", "author_list": "Masi, Enrica; Bellan, Josette; et el." }, { "id": "https://authors.library.caltech.edu/records/y01wa-vt468", "eprint_id": 98310, "eprint_status": "archive", "datestamp": "2023-08-19 09:32:08", "lastmod": "2023-10-18 17:14:29", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Masi-E", "name": { "family": "Masi", "given": "Enrica" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" }, { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth" } } ] }, "title": "Direct Numerical Simulation of High-Pressure Multispecies Turbulent Mixing in the Cold Ignition Regime", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2012 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "A model is proposed for describing mixing of several species under high pressure conditions that relies on a previously proposed model based on governing equations for multispecies mixing that has so far only been exercised for two-species mixing. For the two-species mixing simulations, transport properties were computed from correlated Schmidt (Sc) and Prandtl (Pr) numbers, accurately calculated as functions of the thermodynamic variables, and from a specified Reynolds number value from which an adjusted viscosity value was calculated so as to enable Direct Numerical Simulation (DNS). One of the novelties of the present study is the modeling and computation of multispecies mixing based on a full mass-diffusion matrix, a full thermal-diffusion-factor matrix necessary to include Soret and Dufour effects, and thermal conductivity computed for the species mixture. The scaling of the viscosity necessary for conducting DNS induces a scaling of the other transport properties that respects the accurate values of the Sc numbers and of the Pr number. Computations are performed with five species in the configuration of a temporal mixing layer and the effect of transport properties on species mixing and layer development are analyzed and discussed.", "date": "2012-01-09", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2012-0351", "id_number": "CaltechAUTHORS:20190828-102318779", "isbn": "9781600869365", "book_title": "50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-102318779", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2012-0351", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2012-351", "resource_type": "book_section", "pub_year": "2012", "author_list": "Masi, Enrica; Bellan, Josette; et el." }, { "id": "https://authors.library.caltech.edu/records/p7y7f-nvm82", "eprint_id": 98308, "eprint_status": "archive", "datestamp": "2023-08-19 09:32:01", "lastmod": "2023-10-18 17:14:25", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Radhakrishnan-S", "name": { "family": "Radhakrishnan", "given": "Senthilkumaran" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Explicitly Filtered LES of Single-Phase Compressible Flow", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2012 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "In Large Eddy Simulation (LES), it is often assumed that the filter width is equal to grid spacing. Predictions from such LES are grid-spacing dependent since any Subgrid Scale (SGS) model used in the LES equations is dependent on the resolved flow field which itself varies with grid spacing. Moreover, numerical errors affect the flow field, especially the smallest resolved scales. Thus, predictions using this approach are affected by both modeling and numerical choices. However, grid-spacing independent LES predictions unaffected by numerical choices are necessary to validate LES models through comparison with a trusted template. First, such a template is here created through Direct Numerical Simulation (DNS). Then, simulations are conducted using the conventional LES equations and also LES equations which are here reformulated so that the small-scale producing nonlinear terms in these equations are explicitly filtered (EF) to remove scales smaller than a fixed filter width; this formulation is called EFLES. The conventional LES solution is both grid-spacing and spatial discretization-order dependent, thus showing that both of these numerical aspects affect the flow prediction. The solution of the EFLES equations is grid independent for a high-order spatial discretization on all meshes tested. However, low order discretizations require a finer mesh to reach grid independence. With an eighth order discretization, a filter-width to grid-spacing ratio of two is sufficient to reach grid-independence, while a filter-width to grid-spacing ratio of four is needed to reach grid independence when a fourth or a sixth order discretization is employed. On a grid fine enough to be utilized in a DNS, the EFLES solution exhibits grid independence and does not converge to the DNS solution.", "date": "2012-01-09", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2012-0182", "id_number": "CaltechAUTHORS:20190828-102318608", "isbn": "9781600869365", "book_title": "50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-102318608", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2012-0182", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2012-182", "resource_type": "book_section", "pub_year": "2012", "author_list": "Radhakrishnan, Senthilkumaran and Bellan, J." }, { "id": "https://authors.library.caltech.edu/records/fn4wc-apn28", "eprint_id": 98307, "eprint_status": "archive", "datestamp": "2023-08-19 09:31:58", "lastmod": "2023-10-18 17:14:22", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Radhakrishnan-S", "name": { "family": "Radhakrishnan", "given": "Senthilkumaran" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Explicitly Filtered LES of Two-Phase Flow with Evaporating Droplets", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2012 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "To investigate whether predictions from conventional Large Eddy Simulation (LES), which are known to be grid-spacing and spatial discretization-order dependent, can be rendered grid-spacing and discretization-order independent, we have reformulated LES by explicitly filtering the non-linear terms in the governing equations.1 The encouraging results we obtained1 for compressible single-phase flow motivated our present study in the context of evaporating two-phase flow. Thus, we created a database through Direct Numerical Simulation (DNS) to serve, when filtered, as a template for comparisons with both conventional LES and explicitly-filtered LES (EFLES). Conventional LES is conducted with the Smagorinsky model for the gas phase, and EFLES is also performed with Smagorinsky model; the drop-field SGS model is the same in all these simulations. The results from all these simulations are compared to those from DNS and from the filtered DNS (FDNS). Similar to the single-phase flow findings, the conventional LES method yields solutions which are both grid-spacing and spatial discretization-order dependent. The EFLES solutions are found to be grid-spacing independent for sufficiently large filter-width to grid-spacing ratio, although for the highest discretization order this ratio is larger in the two-phase flow compared to the single-phase flow. For a sufficiently fine grid, the results are also discretization-order independent.", "date": "2012-01-09", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2012-0172", "id_number": "CaltechAUTHORS:20190828-102318509", "isbn": "9781600869365", "book_title": "50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-102318509", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2012-0172", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2012-172", "resource_type": "book_section", "pub_year": "2012", "author_list": "Radhakrishnan, Senthilkumaran and Bellan, J." }, { "id": "https://authors.library.caltech.edu/records/7b2pw-t5720", "eprint_id": 98309, "eprint_status": "archive", "datestamp": "2023-08-19 09:32:05", "lastmod": "2023-10-18 17:14:27", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Modeling of Steady Laminar Flames for One-dimensional Premixed Jets of Heptane/Air and Octane/Air Mixtures", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2012 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "A model is proposed for quasi-one-dimensional steady flame development in the configuration of an inviscid, premixed fuel jet injected into air. The governing equations are written within the framework of a reduced kinetic model based on constituents and species. The reduced kinetic model, previously exercised in a constant-volume perfectlystirred reactor mode, has been successful at predicting ignition and combustion product and temperature evolution for n-heptane, iso-octane, PRF fuel combinations, and mixtures of iso-octane with either n-pentane or iso-hexane. The differential governing equations have the option of an axially variable area and they are coupled with a real gas equation of state. The flame development model accounts for a full diffusion matrix, and thermal conductivity computed for the species mixture. Results from four simulations at various conditions are presented.", "date": "2012-01-09", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2012-0340", "id_number": "CaltechAUTHORS:20190828-102318692", "isbn": "9781600869365", "book_title": "50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190828-102318692", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2012-0340", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2012-340", "resource_type": "book_section", "pub_year": "2012", "author_list": "Harstad, Kenneth G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/k5cjx-eej12", "eprint_id": 98946, "eprint_status": "archive", "datestamp": "2023-08-19 05:13:45", "lastmod": "2023-10-18 17:45:03", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Computation of Laminar Premixed Flames Using Reduced Kinetics Based on Constituents and Species", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2011 by the California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "A model is proposed for quasi-one-dimensional steady flame development in the configuration of an inviscid, premixed fuel jet injected into air. The governing equations are written within the framework of a reduced kinetic model based on constituents and species. The reduced kinetic model, previously exercised in a constant-volume perfectly-stirred reactor mode, has been successful at predicting ignition and combustion product and temperature evolution for n-heptane, iso-octane, PRF fuel combinations, and mixtures of iso-octane with either n-pentane or iso-hexane. The differential governing equations have the option of an axially variable area and they are coupled with a real gas equation of state. The flame development model accounts for a full diffusion matrix, and thermal conductivity computed for the species mixture. Preliminary results are presented.", "date": "2011-01-04", "date_type": "published", "publisher": "AIAA", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2011-415", "id_number": "CaltechAUTHORS:20190930-110459291", "isbn": "9781600869501", "book_title": "49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190930-110459291", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2011-415", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2011-415", "resource_type": "book_section", "pub_year": "2011", "author_list": "Harstad, Kenneth G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/zxfm0-e9v05", "eprint_id": 98944, "eprint_status": "archive", "datestamp": "2023-08-19 05:13:39", "lastmod": "2023-10-18 17:44:58", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Radhakrishnan-S", "name": { "family": "Radhakrishnan", "given": "Senthilkumaran" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Influence of computational drop representation in LES of a droplet-laden mixing layer", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2011 California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc with permission.", "abstract": "The objective of this work is to quantify the influence of the number of computational drops and grid spacing on the accuracy of predicted flow statistics and to possibly identify the minimum number, or, if not possible, the optimal number of computational drops that provides minimal error in flow prediction. For this purpose, Large Eddy Simulation (LES) of a mixing layer with evaporating drops has been performed using the dynamic Smagorinsky model and employing various numbers of computational drops. The LES were performed by reducing the number of physical drops by a factor varying from 8 to 128 to obtain the ensemble of computational drops, and by utilizing either a coarse or a fine grid. A set of first order, second order and drop statistics are extracted from LES predictions and are compared to results obtained by filtering a Direct Numerical Simulation (DNS) database. First order statistics such as Favre averaged streamwise velocity, Favre averaged vapor mass fraction, and the drop streamwise velocity are predicted accurately independent of the number of computational drops and grid spacing. Second order flow statistics depend both on the number of computational drops and on grid spacing. The scalar variance and turbulent vapor flux are predicted accurately by the fine mesh LES only when N R is less than 32 and by the coarse mesh LES reasonably accurately for all N R values. This is attributed to the fact that when the grid spacing is coarsened, the number of drops in a computational cell must be kept approximately the same as in the DNS.", "date": "2011-01-04", "date_type": "published", "publisher": "AIAA", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2011-100", "id_number": "CaltechAUTHORS:20190930-110459109", "isbn": "9781600869501", "book_title": "49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190930-110459109", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2011-100", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2011-100", "resource_type": "book_section", "pub_year": "2011", "author_list": "Radhakrishnan, Senthilkumaran and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/p64b9-3be25", "eprint_id": 82649, "eprint_status": "archive", "datestamp": "2023-08-19 05:02:34", "lastmod": "2024-01-14 05:45:52", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Direct and Large Eddy Simulation of Two-Phase Flows with Evaporation", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2011 Springer Science+Business Media B.V. \n\nThis work was conducted at the Jet Propulsion Laboratory (JPL) of the California Institute of Technology, and was sponsored by the U. S. Department of Energy and the U. S. Air Force Office of Scientific Research under an agreement with the National Aeronautics and Space Administration. Computations were performed on the SGI Origin2000 at the JPL Supercomputing Center.", "abstract": "The modeling of turbulent two-phase flows is a subject of interest both to those who wish to understand and predict natural phenomena (e.g. clouds, tornadoes, volcanic clast dispersion, etc.) and those who wish to design and optimize engineered products (combustion devices based on fuel-spray injection such as gas turbine engines or spark ignition engines, augmenters in military aircraft, spray coating whether for painting or for protection against pests, consumer-product sprays such as those dispensed in cans, medical sprays, etc.). Despite the considerable range of applications and the substantial monetary advantages of successful prediction of turbulent two-phase flows, and despite numerous studies addressing modeling of these flows, there is still a lack of consensus for simulating these flows. The results described below are in the context of volumetrically dilute two-phase flows in which the volume of the condensed phase is negligible with respect to that of the carrier gas (e.g. O(10^(\u22123))) although the ratio of the condensed-phase mass to that of the carrier gas mass can be a substantial fraction (e.g. O(10^(\u22121))) because the density of the condensed phase is larger by a factor of O(10^3) than that of the gas.", "date": "2011", "date_type": "published", "publisher": "Springer", "place_of_pub": "Dordrecht", "pagerange": "151-164", "id_number": "CaltechAUTHORS:20171025-092422756", "isbn": "978-94-007-2481-5", "book_title": "Direct and Large-Eddy Simulation VIII", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171025-092422756", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA/JPL/Caltech" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Air Force Office of Scientific Research (AFOSR)" } ] }, "contributors": { "items": [ { "id": "Kuerten-H", "name": { "family": "Kuerten", "given": "Hans" } }, { "id": "Geurts-B", "name": { "family": "Geurts", "given": "Bernard" } }, { "id": "Armenio-V", "name": { "family": "Armenio", "given": "Vincenzo" } }, { "id": "Fr\u00f6hlich-J", "name": { "family": "Fr\u00f6hlich", "given": "Jochen" } } ] }, "doi": "10.1007/978-94-007-2482-2_25", "resource_type": "book_section", "pub_year": "2011", "author_list": "Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/31y6z-srt68", "eprint_id": 99300, "eprint_status": "archive", "datestamp": "2023-08-19 01:20:33", "lastmod": "2023-10-18 18:13:02", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Alkane Kinetics Reduction Consistent with Turbulence Modeling using Large Eddy Simulation", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc.", "abstract": "A methodology for deriving a reduced kinetic mechanism for alkane oxidation is described, inspired by n-heptane oxidation. The model is based on partitioning the species of the skeletal kinetic mechanism into lights, defined as those having a carbon number smaller than 3, and heavies, which are the complement of the species ensemble. For modeling purposes, the heavy species are mathematically decomposed into constituents, which are similar but not identical to groups in the group additivity theory. From analysis of the n-heptane LLNL skeletal mechanism in conjunction with CHEMKIN II, it is shown that a similarity variable can be formed such that the appropriately non-dimensionalized global constituent molar density exhibits a self-similar behavior over a very wide range of equivalence ratios, initial pressures and initial temperatures that is of interest for predicting n-heptane oxidation. Furthermore, the oxygen and water molar densities are shown to display a quasi-linear behavior with respect to the similarity variable. The light species ensemble is partitioned into quasi-steady and unsteady species. The reduced model is based on concepts consistent with those of Large Eddy Simulation in which functional forms are used to replace the small scales eliminated through Altering of the governing equations; these small scales are unimportant as far as dynamic energy is concerned. Here, we remove the scales deemed unimportant for recovering the thermodynamic energy. The concept is tested by using tabular information from the n-heptane LLNL skeletal mechanism in conjunction with CHEMKIN II utilized as surrogate ideal functions replacing the necessary functional forms. The test reveals that the similarity concept is indeed justified and that the combustion temperature is well predicted, but that the ignition time is overpredicted, which is traced to neglecting a detailed description of the processes lending to the heavies chemical decomposition. To palliate this deficiency, functional modeling is incorporated into our conceptual reduction. This functional modeling includes the global constituent molar density, the enthalpy evolution of the heavies, the contribution to the reaction rate of the unsteady lights from other light species and from the heavies, the molar density evolution of oxygen and water, and the mole &actions of the quasi-steady light species. The model is compact in that there are only nine species-related progress variables. Results are presented showing the performance of the model for predicting the temperature and species evolution for n-heptane. The model reproduces the ignition time over a wide range of equivalence ratios, initial pressure and initial temperature. Preliminary results for iso-octane using the full mechanism are also presented, showing encouragingly that the concept may be generalized to other alkanes. The utility of the model and possible improvements are discussed.", "date": "2010-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2010-1514", "id_number": "CaltechAUTHORS:20191016-111202608", "isbn": "978-1-60086-959-4", "book_title": "48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191016-111202608", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2010-1514", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2010-1514", "resource_type": "book_section", "pub_year": "2010", "author_list": "Harstad, Kenneth G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/ktrwq-crm60", "eprint_id": 99299, "eprint_status": "archive", "datestamp": "2023-08-19 01:20:30", "lastmod": "2023-10-18 18:13:00", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Taskinoglu-E-S", "name": { "family": "Taskinoglu", "given": "Ezgi S." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Large Eddy Simulations of Temporal Mixing Layers Under Supercritical Thermodynamic Conditions: O_2/H_2", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission.", "abstract": "A Direct Numerical Simulation (DNS) database of supercritical temporal mixing layer simulations of binary mixtures is studied to identify the Large Eddy Simulation (LES) subgrid scale model needs for high pressure flows. For the oxygen/hydrogen (OH) mixture studied here, an earlier a priori study showed that in addition to the usual subgrid scale flux terms, a new term in the filtered energy equation must be modeled. A model formulation was proposed for this term called heat flux correction (q-correction), but the model was only partially successful in the a priori tests. In this study, the earlier a priori analysis is revisited to investigate the reasons for the limited success of the previously proposed model for the q-correction. In addition, a new modeling strategy is proposed and examined a priori. Finally, an a posteriori study is conducted to test the viability of the newly proposed model.", "date": "2010-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2010-206", "id_number": "CaltechAUTHORS:20191016-110320677", "isbn": "978-1-60086-959-4", "book_title": "48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191016-110320677", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2010-206", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2010-206", "resource_type": "book_section", "pub_year": "2010", "author_list": "Taskinoglu, Ezgi S. and Bellan, J." }, { "id": "https://authors.library.caltech.edu/records/hp6p7-fs071", "eprint_id": 99309, "eprint_status": "archive", "datestamp": "2023-08-19 01:20:36", "lastmod": "2023-10-18 18:13:26", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Radhakrishnan-S", "name": { "family": "Radhakrishnan", "given": "Senthilkumaran" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "On Experimental Data for Validation of Large-Eddy Simulation of Evaporating Droplets in a Mixing Layer", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 by California Institute of Technology. Published by American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "Large Eddy Simulation (LES) of a mixing layer with evaporating drops has been performed with various Sub Grid Scale (SGS) models. The objective of this work is to identify the statistics that are essential for validation of LES and to quantify the accuracy of their prediction by the SGS model. Four SGS models namely, the dynamic Smagorinsky (SM) model, the dynamic Gradient (GR) model, the dynamic mixed model which combines SM with a Scale-Similarity term and the dynamic Clark model which combines the SM and GR gradients are tested. A set of first order, second order and drop conditioned statistics from LES predictions are compared to the Direct Numerical Simulation (DNS) results.\nFirst order statistics such as Favre averaged streamwise velocity, Favre averaged vapor mass fraction, and the drop streamwise velocity are predicted accurately by all the models tested. Second order statistics such as the streamwise Reynolds stress, the cross-stream Reynolds stress, the spanwise Reynolds stress and the vapor mass fraction fluctuation variance are predicted with a maximum of 15% error by the SGS models tested. The dynamic Smagorinsky model predicts the drop conditioned statistics, which describe the segregation of the drops in high strain rate region, more accurately compared to the other models tested.", "date": "2010-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2010-204", "id_number": "CaltechAUTHORS:20191016-150432060", "isbn": "978-1-60086-959-4", "book_title": "48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191016-150432060", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "collection": "CaltechAUTHORS", "other_numbering_system": { "items": [ { "id": "2010-204", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2010-204", "resource_type": "book_section", "pub_year": "2010", "author_list": "Radhakrishnan, Senthilkumaran and Bellan, J." }, { "id": "https://authors.library.caltech.edu/records/he34j-77d92", "eprint_id": 100788, "eprint_status": "archive", "datestamp": "2023-08-20 00:38:46", "lastmod": "2023-10-18 21:52:02", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Taskinoglu-E-S", "name": { "family": "Taskinoglu", "given": "Ezgi S." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "An a Posteriori Study of a DNS Database Describing Supercritical Binary-Species Mixing", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2009 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. \n\nPublished online: 15 Jun 2012.", "abstract": "Large Eddy Simulation (LES) a posteriori study is conducted for a mixing layer which initially contains different species in the lower and upper streams, and where the initial pressure is larger than the critical pressure of either species. An initially imposed-vorticity perturbation promotes roll-up and a double pairing of four initial spanwise vortices to reach a transitional state. The LES equations consist of the differential conservation equations coupled with a real-gas equation of state, and the equation set utilizes transport properties depending on the thermodynamic variables. Unlike all LES models to date, the differential equations contain, additional to the Subgrid Scale (SGS) fluxes, a new SGS term which is a pressure correction in the momentum equation. This additional term results from altering of the Direct Numerical Simulation (DNS) equations and represents the gradient of the difference between the filtered pressure and the pressure computed from the filtered flow field. A previous a priori analysis, using a DNS database for the same configuration, found this term to be of leading order in the momentum equation, a fact traced to the existence of high density-gradient magnitude regions that populated the entire flow; in that study, models were proposed for the SGS fluxes as well as this new term. In the present study, the previously-proposed constant-coefficient SGS-flux models of the a priori investigation are tested a posteriori in LES devoid or including the SGS pressure correction term. The present pressure-correction model is different from, and more accurate and less computationally intensive than that of the a priori study. The constant-coefficient SGS-flux models encompass the Smagorinsky (SMC), in conjunction with the Yoshizawa (YO) model for the trace, the Gradient (GRC) and the Scale Similarity (SSC) models, all exercised with the a priori study constant coefficients calibrated at the transitional state. The LES comparison is performed with the fitered-and-coarsened (FC) DNS which represents an ideal LES solution. Expectably, when the LES model is devoid of SGS terms, it is shown to be considerably inferior to models containing SGS effects. Among models containing SGS effects, those including the pressure-correction term are substantially superior to those devoid of it. The sensitivity of the predictions to the initial conditions and grid size are also investigated.", "date": "2009-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2009-808", "id_number": "CaltechAUTHORS:20200117-101910142", "isbn": "978-1-60086-973-0", "book_title": "47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200117-101910142", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2009-808", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2009-808", "resource_type": "book_section", "pub_year": "2009", "author_list": "Taskinoglu, Ezgi S. and Bellan, J." }, { "id": "https://authors.library.caltech.edu/records/4jve6-r0p63", "eprint_id": 100780, "eprint_status": "archive", "datestamp": "2023-08-20 00:38:21", "lastmod": "2023-10-18 21:51:43", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Modeling of Alkane Oxidation using Constituents and Species", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2009 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. \n\nPublished online: 15 Jun 2012.", "abstract": "A chemical kinetics reduction model is proposed for alkane oxidation in air that is baaed on a parallel methodology to that used in turbulence modeling in the context of Large Eddy Simulation. The objective of kinetic modeling is to predict the heat release and temperature evolution. In an a priori step, a categorization of time scales is first conducted to identify scales that must be modeled and scales that must be computed using progress variables based on the model for the other scales. First, a decomposition of heavy (carbon number greater or equal to 3) hydrocarbons into constituents is proposed. Examination of results obtained using the LLNL heptane-oxidation database in conjunction with Chemkin II shows that (i) with appropriate scaling, the total constituent mole fraction behaves in a self-similar manner and the total constituent molar density rate follows a quasi-steady behavior, and (ii) the light species can be partitioned into two subsets according to whether\nthey are quasi-steady (nine species) or unsteady (11 species). The twelve progress variables represented by the total constituent molar density and the molar densities of the unsteady light species are defined to be a base from which the system's behavior can be reproduced. This is a dramatic reduction from the 160 species (progress variables) and 1540 reactions in the LLNL set to 12 progress variables, 16 quasi-steady rates (associated with heavy species), 162 conventional reaction rates (light species) and 11 other functional forms (i.e. fits for the mean heavy-species heat capacity at constant pressure, the enthalpy release rate of the heavy species, and the molar fraction of quasi-steady light species). A summary of the model is presented explaining the curve fits that constitute the model, namely (1) for the constituent molar density rate a long with the corresponding enthalpy production rate, (2) for the quasi-steady species mole fraction, and (3) for the contribution from the heavy species to the unsteady light species reaction rates. The proposed kinetic mechanism is valid over a pressure range from atmospheric to 60 bar, temperatures from 600 K to 2500 K and equivalence ratio1 from 0.125 to 8. This range encompasses diesel, HCCI and gas turbine engines, including cold ignition; and NO_x, CO and soot pollutant formation in the lean and rich regimes, respectively. Highlights of the a priori model results are illustrated for a variety of initial conditions. Results from a posteriori tests are shown in which the model predictions for the unsteady light species and the temperature are compared to the equivalent quantities baaed on the LLNL dataset.", "date": "2009-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2009-1368", "id_number": "CaltechAUTHORS:20200117-081103466", "isbn": "978-1-60086-973-0", "book_title": "47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200117-081103466", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2009-1368", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2009-1368", "resource_type": "book_section", "pub_year": "2009", "author_list": "Harstad, Kenneth G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/8y0qh-ye325", "eprint_id": 100787, "eprint_status": "archive", "datestamp": "2023-08-20 00:38:41", "lastmod": "2023-10-18 21:52:00", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Okong'o-N-A", "name": { "family": "Okong'o", "given": "N. A." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Small-Scale Dissipation in Supercritical, Transitional Mixing Layers", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2009 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. \n\nPublished online: 15 Jun 2012.", "abstract": "The dissipation and small-scale dissipation is calculated for transitional states obtained elsewhere from Direct Numerical Simulations (DNS) of temporal, supercritical mixing layers for two species systems, O\u2082/H\u2082 and C\u2087H\u2081\u2086/N\u2082, so as to understand their species-independent and species-dependent aspects. The effect of filter size on the results was also investigated, with filtering exclusively performed in the dissipation regime of the energy spectrum. Both domain-average dissipation and the small-scale dissipation were analyzed in terms of the three mode contributions to them due to the viscous, heat and species-mass fluxes. The species-mass flux originated contribution dominates both the dissipation and the small-scale dissipation for all simulations and its percentage of the total dissipation or of the small-scale dissipation varies in a very small range across the species system, the initial Reynolds number and the perturbation wavelength used to excite the layer. For a filter size that is four times the DNS grid size, the proportion of each small-scale dissipation mode in the total small-scale dissipation is similar to that obtained at the DNS scale, indicating a scale similarity. It was also found that the percentage of total small-scale dissipation in the total DNS dissipation is only species-system and filter size dependent but nearly independent of the initial conditions. With filter size increase, the increase in the small-scale dissipation portion of the DNS dissipation has similar functional variation for both species systems, although the fraction reached by C\u2087H\u2081\u2086/N\u2082 layers is much larger than for O\u2082/H\u2082 ones. Normalization by the results obtained at the smallest filter size led to highlighting several aspects that are only species-system dependent with increasing the filter size. Backscatter was shown to occur over a substantial percentage of the computational domain, and its magnitude was found to be a substantial fraction of the positive small-scale dissipation. A four fold increase in filter size decreased the spatial extent of backscatter by only at most 32%, 13% and 7.5% for the viscous, heat and species-mass flux originated modes. The implications or these results for Larger Eddy Simulation modeling are discussed.", "date": "2009-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2009-807", "id_number": "CaltechAUTHORS:20200117-100544207", "isbn": "978-1-60086-973-0", "book_title": "47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200117-100544207", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2009-807", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2009-807", "resource_type": "book_section", "pub_year": "2009", "author_list": "Okong'o, N. A. and Bellan, J." }, { "id": "https://authors.library.caltech.edu/records/g9qg0-nf078", "eprint_id": 102687, "eprint_status": "archive", "datestamp": "2023-08-19 22:00:13", "lastmod": "2023-10-20 00:24:36", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "A Simplified Model of Alkane Oxidation", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc.", "abstract": "A simplified model is proposed for the kinetics of alkane oxidation in air, based on a decomposition of heavy (carbon number greater or equal to 3) hydrocarbons into a 13 constituent radical base. The behavior of this base is examined in test computations for n-heptane utilizing Chemkin II with LLNL data inputs, placing emphasis on modeling to predict the heat release and temperature evolution. A normalized temperature was constructed which when used to plot the total constructed molar density divided by the product of the equivalence ratio and a nondimensional pressure, reveals a self-similar behavior of the plotted variable over a wide range of initial pressures and equivalence ratios. Examination of the LLNL kinetics shows that the total constituent molar density rate follows a quasi-steady behavior. This reaction rate was curve fitted along with the corresponding enthalpy production. The fits are shown against the normalized temperature for various equivalence ratios and initial nondimensional pressures and comparisons with the LLNL kinetics are very favorable. The model reduces the LLNL n-heptane mechanism from 160 species (progress variables) and 1540 reactions to 12 progress variables, 16 quasi-steady rates (associated with heavy species), 162 conventional reaction rates (light species) and 11 other functional forms. (i.e. fits for the mean heavy-species heat capacity at constant pressure, the enthalpy release rate of the heavy species, and the molar fraction of quasi-steady light species). The proposed kinetic mechanism is valid over a pressure range from atmospheric to 60 bar, temperatures from 600 K to 2500 K and equivalence ratios from 0.125 to 8. This range encompasses diesel, HCCI and gas turbine engines, including cold ignition; and NO_x, CO and soot pollutant formation in the lean and rich regimes, respectively.", "date": "2008-01-07", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2008-975", "id_number": "CaltechAUTHORS:20200421-083907781", "isbn": "978-1-62410-128-1", "book_title": "46th AIAA Aerospace Sciences Meeting and Exhibit", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200421-083907781", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2008-975", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2008-975", "resource_type": "book_section", "pub_year": "2008", "author_list": "Harstad, Kenneth G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/b5w4y-af562", "eprint_id": 103012, "eprint_status": "archive", "datestamp": "2023-08-19 22:00:16", "lastmod": "2023-10-20 00:42:04", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Selle-L-C", "name": { "family": "Selle", "given": "Laurent C." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Modeling Requirements for LES of Fully Multicomponent Fuel Flows", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "The Large Eddy Simulation (LES) equations for multi-component (MC) fuel two-phase flow are derived from the Direct Numerical Simulation (DNS) equations by filtering the DNS equations using a top-hat filter. The filtered equations contain two categories of subgrid-scale (SGS) terms that must be modeled: (1) SGS terms and (2) terms representing the 'LES assumptions'. In contrast to single-component (SC) fuels, it is shown that two LES formulations, rather than a single one, are possible, and these formulations are not equivalent. Assumptions not present in corresponding SC LES equations are examined and assessed. Criteria are proposed to select the formulation best suited for LES. These criteria are used in conjunction with evaluations based on a DNS database and lead to the final LES equations. This analysis represents the precursor to a future study for modeling the MC LES equations.", "date": "2008-01-07", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2008-983", "id_number": "CaltechAUTHORS:20200506-071125715", "isbn": "978-1-62410-128-1", "book_title": "46th AIAA Aerospace Sciences Meeting and Exhibit", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200506-071125715", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2008-983", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2008-983", "resource_type": "book_section", "pub_year": "2008", "author_list": "Selle, Laurent C. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/kt3q6-frf90", "eprint_id": 102173, "eprint_status": "archive", "datestamp": "2023-08-19 22:00:09", "lastmod": "2023-10-19 23:55:08", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Selle-L-C", "name": { "family": "Selle", "given": "L. C." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" }, { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "K. G." } } ] }, "title": "Modeling of the Energy Equation for LES of Flows at Supercritical Pressure", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, inc., with permission.", "abstract": "A database of transitional Direct Numerical Simulation (DNS) realizations of a supercritical mixing layer is analyzed for understanding small-scale behavior and examining Subgrid Scale (SGS) models duplicating that behavior. Initially, the mixing layer contains a single chemical species in each of the two streams, and a perturbation promotes roll-up and a double pairing of the four spanwise vortices initially present. The database encompasses three combinations of chemical species, several perturbation wavelengths and amplitudes, and several initial Reynolds numbers specifically chosen for the sole purpose of achieving transition. The DNS equations are the Navier Stokes, total energy and species equations coupled to a real gas equation of state; the fluxes of species and heat include the Soret and Dufour effects. The Large Eddy Simulation (LES) equations are derived from the DNS ones through Altering. Compared to the DNS equations, two types of additional terms are identified in the LES equations: SGS fluxes and other terms for which either assumptions or models are necessary. The focus is here on the energy equation. The magnitude of all terms in this filtered DNS equation is analyzed on the DNS database, with special attention to terms that could possibly be neglected. It is shown that in contrast to atmospheric-pressure gaseous flows, there is a new term that must be modeled in this equation. This new term can be thought to result from the filtering of the strongly nonlinear equation of state, and is associated with high density-gradient magnitude regions both found in DNS and observed experimentally in fully-turbulent high-pressure flows. A priori modeling approaches for the energy-equation additional term are proposed, all of which must ultimately be tested in LES to show viability.", "date": "2008-01-07", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2008-948", "id_number": "CaltechAUTHORS:20200330-131934118", "isbn": "978-1-62410-128-1", "book_title": "46th AIAA Aerospace Sciences Meeting and Exhibit", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200330-131934118", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2008-948", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2008-948", "resource_type": "book_section", "pub_year": "2008", "author_list": "Selle, L. C.; Bellan, J.; et el." }, { "id": "https://authors.library.caltech.edu/records/sf8zg-8g646", "eprint_id": 102992, "eprint_status": "archive", "datestamp": "2023-08-19 19:30:40", "lastmod": "2023-10-20 00:41:06", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "A New Method in Modeling and Simulations of Complex Oxidation Chemistry", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2007 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "A simplified model is proposed for the kinetics of alkane oxidation in air, based on a decomposition of heavy (carbon number \u22653) hydrocarbons into a 13 constituent radical base. The behavior of this base is examined in test computations for heptane utilizing Chemkin II with LLNL data inputs. Emphasis is placed on prediction of the heat release and temperature evolution. At stoichiometric conditions, the total constituent molar density was found to follow a quasi-steady rate which is a simplification in the modeling of its reaction rate.", "date": "2007-01-08", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. \t2007-1433", "id_number": "CaltechAUTHORS:20200505-073936057", "isbn": "978-1-62410-012-3", "book_title": "45th AIAA Aerospace Sciences Meeting and Exhibit", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200505-073936057", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2007-1433", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2007-1433", "resource_type": "book_section", "pub_year": "2007", "author_list": "Harstad, Kenneth G. and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/dc26g-0ct41", "eprint_id": 103013, "eprint_status": "archive", "datestamp": "2023-08-19 19:30:44", "lastmod": "2023-10-20 00:42:06", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Selle-L-C", "name": { "family": "Selle", "given": "Laurent C." } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" }, { "id": "Harstad-K-G", "name": { "family": "Harstad", "given": "Kenneth G." } } ] }, "title": "Novel Subgrid Modeling of the LES Equations Under Supercritical Pressure", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2007 by California Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.", "abstract": "Transitional states obtained from Direct Numerical Simulation (DNS) of a supercritical mixing layer are analyzed for studying small-scale behavior and assessing the ability of Subgrid Scale (SGS) models to duplicate that behavior. Initially, the mixing layer contains a single chemical species in each of the two streams, and a perturbation promotes rollup and a double pairing of the four spanwise vortices initially present. The database encompasses three combinations of chemical species, several perturbation wavelengths and amplitudes, and several initial Reynolds numbers specifically chosen for the sole purpose of achieving transition. The Large Eddy Simulation (LES) equations are derived from the DNS ones through filtering. This filtering leads to two types of additional terms in the LES compared to the DNS equations : SGS fluxes and other terms for which either assumptions or models are necessary. The magnitude of all terms in the LES conservation equations is analyzed on the DNS database, with special attention to terms that could possibly be neglected. It is shown that in contrast to atmospheric-pressure gaseous flows, there are two new terms that must be modeled: one in each of the momentum and the energy equations. Discussed is a model for the momentum-equation additional term. This model performs well at small filter size but deteriorates as the filter size increases, highlighting the necessity of ensuring appropriate grid resolution in LES.", "date": "2007-01-08", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "Art. No. 2007-568", "id_number": "CaltechAUTHORS:20200506-071823327", "isbn": "978-1-62410-012-3", "book_title": "45th AIAA Aerospace Sciences Meeting and Exhibit", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200506-071823327", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2007-568", "name": "AIAA Paper" } ] }, "doi": "10.2514/6.2007-568", "resource_type": "book_section", "pub_year": "2007", "author_list": "Selle, Laurent C.; Bellan, Josette; et el." }, { "id": "https://authors.library.caltech.edu/records/nxdxy-1c692", "eprint_id": 82735, "eprint_status": "archive", "datestamp": "2023-08-19 15:09:59", "lastmod": "2024-01-14 05:46:45", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Subcritical/Supercritical Droplet Cluster Behavior in Dense and Dilute Regions of Sprays", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2004 by the American Institute of Aeronautics and Astronautics. The U.S. Government has a royalty-free license to exercise all rights under the Copyright claimed here in for Governmental purposes. All other rights are reserved by the copyright owner.", "abstract": "Concern for efficiently, stability, and safety margins of bipropellant combustion in rocket engines has prompted the investigation of many specific aspects of spray behavior previously not studied. Thus, early studies of combustion in liquid rocket engines were based on the results of the classical single-component, isolated drop combustion at atmospheric pressure. Although the results from these studies provided a baseline for understanding some of the phenomena occurring in liquid rocket engines, they fail to explain important observations and facts obtained from examining rocket performance after many flights. Examples are the loss of about 3% of the liquid oxygen (LOX, one of the propellants) that exists unburned, and the existence of striations on the inner wall of engines after a flight. It then becomes apparent that many significant issues of liquid rocket spray combustion were not addressed by the early models, and that to mitigate existing problems, it is necessary to understand aspect previously unexplored.", "date": "2005", "date_type": "published", "place_of_pub": "Reston, VA", "pagerange": "323-338", "id_number": "CaltechAUTHORS:20171027-130401462", "isbn": "9781600864575", "book_title": "Liquid Rocket Thrust Chambers", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171027-130401462", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Popp-M", "name": { "family": "Popp", "given": "Michael" } }, { "id": "Hulka-J", "name": { "family": "Hulka", "given": "James" } }, { "id": "Yang-Vigor", "name": { "family": "Yang", "given": "Vigor" } }, { "id": "Habiballah-M", "name": { "family": "Habiballah", "given": "Mohammed" } } ] }, "doi": "10.2514/5.9781600866760.0323.0338", "resource_type": "book_section", "pub_year": "2005", "author_list": "Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/dbse8-md809", "eprint_id": 82606, "eprint_status": "archive", "datestamp": "2023-08-19 08:48:57", "lastmod": "2024-01-14 05:45:30", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Okong'o-N-A", "name": { "family": "Okong'o", "given": "Nora" } }, { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Characteristics of Supercritical Transitional Temporal Mixing Layers", "ispublished": "unpub", "full_text_status": "public", "keywords": "Supercritical transitional mixing layer", "note": "\u00a9 2002 Springer Science+Business Media Dordrecht.", "abstract": "Several Direct Numerical Simulation realizations of supercritical, three-dimensional, temporal mixing layers are used to investigate aspects of interest to turbulent combustion. The realizations are based on a model previously developed that accounts for the enlarged transport matrix at supercritical conditions (Soret and Dufour effects), for real gas equations of state, and for variable Schmidt and Prandtl numbers. This model is exercised for two very different sets of binary species, heptane/nitrogen and oxygen/hydrogen, to obtain transitional states for mixing layers excited at different perturbation wavelengths. Visualizations of the transitional states show that all layers develop convoluted regions of high density gradient magnitude (HDGM), which result both from the distortion of the initial density stratification boundary and from mixing. The species mass fraction in these HDGM regions is very weakly dependent of the perturbation wavelength. The existence of the HDGM regions, independent of the perturbation wavelength, indicates that they may be a feature of spatial mixing layers, and furthermore have a similar mass fraction composition. Evaluations of the applicability of the assumed PDF method for describing supercritical transitional flows shows that neither the \u00df density nor the Gaussian are appropriate representations of the conserved scalar, and that the PDFs of the partial densities and the temperature are correlated, invalidating the typical model of the reaction rate as the product of the marginal PDFs.", "date": "2002", "date_type": "published", "publisher": "Springer", "place_of_pub": "Dordrecht", "pagerange": "59-71", "id_number": "CaltechAUTHORS:20171024-075404739", "isbn": "978-90-481-6074-7", "book_title": "IUTAM Symposium on Turbulent Mixing and Combustion", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171024-075404739", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Pollard-A", "name": { "family": "Pollard", "given": "A." } }, { "id": "Candel-S", "name": { "family": "Candel", "given": "S." } } ] }, "doi": "10.1007/978-94-017-1998-8_5", "resource_type": "book_section", "pub_year": "2002", "author_list": "Okong'o, Nora and Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/56ybc-00b72", "eprint_id": 82662, "eprint_status": "archive", "datestamp": "2023-08-19 03:49:11", "lastmod": "2023-10-17 22:35:25", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "J." }, "orcid": "0000-0001-9218-7017" }, { "id": "Lathouwers-D", "name": { "family": "Lathouwers", "given": "D." } } ] }, "title": "Tar production from biomass pyrolysis in a fluidized bed reactor: A novel turbulent multiphase flow formulation", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 1999 Elsevier Science.", "abstract": "A novel multiphase flow model is presented for describing the pyrolysis of biomass \nin a 'bubbling' fluidized bed reactor. The mixture of biomass and sand in a gaseous\nflow is conceptualized as a particulate phase composed of two classes interacting with \nthe carrier gaseous flow. The solid biomass is composed of three initial species: cellulose, \nhemicellulose and lignin. From each of these initial species, two new solid species originate\nduring pyrolysis: an 'active' species and a char, thus totaling seven solid-biomass species. \nThe gas phase is composed of the original carrier gas (steam), tar and gas; the last \ntwo species originate from the volumetric pyrolysis reaction. The conservation equations \nare derived from the Boltzmann equations through ensemble averaging. Stresses in the \ngaseous phase are the sum of the Newtonian and Reynolds (turbulent) contributions. \nThe particulate phase stresses are the sum of collisional and Reynolds contributions. \nHeat transfer between phases, and heat transfer between classes in the particulate phase\nis modeled, the last resulting from collisions between sand and biomass. Closure of the \nequations must be performed by modeling the Reynolds stresses for both phases. The\nresults of a simplified version (first step) of the model are presented.", "date": "1999", "date_type": "published", "publisher": "Elsevier", "place_of_pub": "Oxford", "pagerange": "1-7", "id_number": "CaltechAUTHORS:20171025-124117232", "isbn": "0-08-043019-8", "book_title": "Biomass: a growth opportunity in green energy and value-added products", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171025-124117232", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Overend-R-P", "name": { "family": "Overend", "given": "Ralph P." } }, { "id": "Chornet-C", "name": { "family": "Chornet", "given": "Esteban" } } ] }, "resource_type": "book_section", "pub_year": "1999", "author_list": "Bellan, J. and Lathouwers, D." }, { "id": "https://authors.library.caltech.edu/records/6rsz2-vjt73", "eprint_id": 82736, "eprint_status": "archive", "datestamp": "2023-08-20 07:00:22", "lastmod": "2024-01-14 05:46:47", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Fundamentals of Dynamics and Evaporation in Clusters of Drops Embedded into Vortices", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1994 by the American Institute of Aeronautics and Astronautics. The U.S. Government has a royalty-free license to exercise all rights under the Copyright claimed herein for Governmental purposes. All other rights are reserved by the copyright owner.", "abstract": "Drops in vortices are an inherent feature of a spray whether a spray is combusting or not. The clustering of injected drops into round jets has been observed by Longmire and Eaton; each cluster remains embedded in a coherent vortex. The train of these vortices forms the shear layer at the edge of the jet. Clustering of drops in sprays has also been observed by McDonell et al. in both cold flows and combusting sprays and by Rudoff et al. Recently, Mizutani et al. confirmed the previous observation of Allen and Hanson, who identified closed-surface flames surrounding portions of space much larger than individual drops; these flames presumably enclosed clusters of drops. It is obvious that for drops to be clustered in a convective environment, there must be a fluid dynamical feature which maintains them in a cluster. Since vortices occur in all flows of practical interest, it is only natural to assume that drops embedded in vortices form entities of crucial interest in sprays.\nThis chapter is devoted to describing formulations of clusters of drops in vertical flows. Further, it is also explained how there entities can be used to portray spray shear layers and how results obtained with such models can aid in the qualitative understanding of the layers. Finally, conclusions are presented summarizing the significance of the results and pointing to further directions for this work.", "date": "1996", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Reston, VA", "pagerange": "381-397", "id_number": "CaltechAUTHORS:20171027-132428140", "isbn": "978-1-56347-175-9", "book_title": "Recent Advances in Spray Combustion: Spray Atomization and Drop Burning Phenomena", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171027-132428140", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Kuo-K-K", "name": { "family": "Kuo", "given": "Kenneth K." } } ] }, "doi": "10.2514/5.9781600866418.0381.0397", "resource_type": "book_section", "pub_year": "1996", "author_list": "Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/1vr9z-fv591", "eprint_id": 82737, "eprint_status": "archive", "datestamp": "2023-08-20 05:10:51", "lastmod": "2023-10-17 22:38:41", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Dynamics and Thermodynamics of Dense and Dilute Clusters of Drops", "ispublished": "unpub", "full_text_status": "public", "note": "This work is provided through the courtesy of the Jet Propulsion Laboratory, California Institute of Technology.\n\nPublished - 94-1480.pdf
", "abstract": "Collective drop behavior is encountered in sprays produced for a variety of applications: fuel sprays produced for combusting devices, metal sprays produced for coating, paint sprays, printer sprays, atmospheric clouds, etc. There is experimental evidence that clusters of drops exist both in combusting [1], [2], [3], [4], [5], and non-combusting sprays for atomizers used in combusting devices [6], [3], [4]. Clusters of drops have also been observed in round jets laden with solid glass beads [7], although\nthe glass beads (of 55p radius) did not behave entirely like liquid drops due to their large inertia. The existence of these clusters of drops indicates that the interaction\namong the drops is important in determining the dynamics of the drops because the drop proximity changes the flow around the individual drops in ways that affects the drag on each drop. Additionally, if there is a phase change between the liquid drops and the gaseous surroundings (either evaporation or condensation), this will\nalso influence the flow around the individual drops; and phase change is also affected by the drop proximity. If evaporation occurs, it is the drop heat up that is affected\nby drop proximity and the build up of fuel vapor in the interstitial space among drops might lead to saturation of the gas, resulting in termination of evaporation. If\ncondensation occurs, such as in atmospheric clouds, the rate of mass transfer to the hotter liquid drops from the colder gas results in the reduction of the temperature\ndifferential between phases and thus might terminate phase change; and the rate of mass transfer depends upon drop proximity.", "date": "1995", "date_type": "published", "publisher": "Begell House", "place_of_pub": "New York, NY", "pagerange": "177-194", "id_number": "CaltechAUTHORS:20171027-134030911", "isbn": "9781567000511", "book_title": "IUTAM Symposium on Mechanics and Combustion of Droplets and Sprays", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171027-134030911", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Chiu-H-H", "name": { "family": "Chiu", "given": "H. H." } }, { "id": "Chigier-N-A", "name": { "family": "Chigier", "given": "Norman A." } } ] }, "primary_object": { "basename": "94-1480.pdf", "url": "https://authors.library.caltech.edu/records/1vr9z-fv591/files/94-1480.pdf" }, "resource_type": "book_section", "pub_year": "1995", "author_list": "Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/kag8a-t2q22", "eprint_id": 82652, "eprint_status": "archive", "datestamp": "2023-08-20 02:21:44", "lastmod": "2023-10-17 22:35:03", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "The Jet Propulsion Laboratory Space Exploration: Past, Present and Future", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1993 Israel Society of Aeronautics and Astronautics. \n\nThe work described in this paper was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The information presented here was provided by the JPL Public Information Office through their science summaries. However, opinions presented in this manuscript are only those of the author and do not necessarily represent those of JPL.\n\nPublished - 93-0037.pdf
", "abstract": "The most recent scientific results from space exploration carried out by the Jet Propulsion Laboratory (JPL) are discussed. \n\nTo understand these results, a brief background of JPL's history is presented, followed by a description of the Deep Space Network, JPL's system of antennas which communicates with spacecraft. \n\nThe results from the missions of Voyager 1 and Voyager 2 are described. The atmosphere, rings, satellites and\nmagnetospheres of Jupiter, Saturn, Uranus and Neptune are discussed with particular emphasis on novelty of the discoveries and the challenges encountered in explaining them. \n\nA brief discussion of the impact of spray research upon space exploration follows. This is because most recently launched missions used liquid fueled rockets to escape Earth's gravity. \n\nA summary of future missions and the National Aeronautics and Space Administration's new policies is presented in the conclusion.", "date": "1993-02", "date_type": "published", "publisher": "Israel Society of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20171025-103038529", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171025-103038529", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA/JPL/Caltech" } ] }, "contributors": { "items": [ { "id": "Burcat-A", "name": { "family": "Burcat", "given": "A." } } ] }, "primary_object": { "basename": "93-0037.pdf", "url": "https://authors.library.caltech.edu/records/kag8a-t2q22/files/93-0037.pdf" }, "resource_type": "book_section", "pub_year": "1993", "author_list": "Bellan, Josette" }, { "id": "https://authors.library.caltech.edu/records/8gqzy-tj052", "eprint_id": 82733, "eprint_status": "archive", "datestamp": "2023-08-19 23:31:53", "lastmod": "2024-01-14 05:46:43", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bellan-J", "name": { "family": "Bellan", "given": "Josette" }, "orcid": "0000-0001-9218-7017" } ] }, "title": "Liquid Drop Behavior in Dense and Dilute Clusters", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1991 by the American Institute of Aeronautics and Astronautics. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental purposes. All other rights are reserved by the copyright owner.", "abstract": "[No abstract]", "date": "1991", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_pub": "Washington, DC", "pagerange": "547-583", "id_number": "CaltechAUTHORS:20171027-112558181", "isbn": "978-1-60086-608-1", "book_title": "Numerical Approaches to Combustion Modeling", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171027-112558181", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Oran-E-S", "name": { "family": "Oran", "given": "Elaine S." } }, { "id": "Boris-J-P", "name": { "family": "Boris", "given": "Jay P." } } ] }, "doi": "10.2514/5.9781600866081.0547.0583", "resource_type": "book_section", "pub_year": "1991", "author_list": "Bellan, Josette" } ]