[ { "id": "https://authors.library.caltech.edu/records/1ya2r-9a428", "eprint_id": 120088, "eprint_status": "archive", "datestamp": "2023-08-20 09:02:13", "lastmod": "2023-10-25 16:52:05", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Renn-Peter-I", "name": { "family": "Renn", "given": "Peter I" }, "orcid": "0000-0002-5735-3873" }, { "id": "Wang-Cong-AERO", "name": { "family": "Wang", "given": "Cong" }, "orcid": "0000-0002-8271-5637" }, { "id": "Lale-Sahin", "name": { "family": "Lale", "given": "Sahin" }, "orcid": "0000-0002-7191-346X" }, { "id": "Li-Zongyi", "name": { "family": "Li", "given": "Zongyi" }, "orcid": "0000-0003-2081-9665" }, { "id": "Anandkumar-A", "name": { "family": "Anandkumar", "given": "Anima" }, "orcid": "0000-0002-6974-6797" }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "Morteza" }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Forecasting subcritical cylinder wakes with Fourier Neural Operators", "ispublished": "unpub", "full_text_status": "public", "note": "This work was supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301, Bren endowed chair, Kortschak Scholars, PIMCO Fellows, Amazon AI4Science Fellows, and the Center for Autonomous Systems and Technologies at Caltech.\n\n
Submitted - 2301.08290.pdf
", "abstract": "We apply Fourier neural operators (FNOs), a state-of-the-art operator learning technique, to forecast the temporal evolution of experimentally measured velocity fields. FNOs are a recently developed machine learning method capable of approximating solution operators to systems of partial differential equations through data alone. The learned FNO solution operator can be evaluated in milliseconds, potentially enabling faster-than-real-time modeling for predictive flow control in physical systems. Here we use FNOs to predict how physical fluid flows evolve in time, training with particle image velocimetry measurements depicting cylinder wakes in the subcritical vortex shedding regime. We train separate FNOs at Reynolds numbers ranging from Re = 240 to Re = 3060 and study how increasingly turbulent flow phenomena impact prediction accuracy. We focus here on a short prediction horizon of ten non-dimensionalized time-steps, as would be relevant for problems of predictive flow control. We find that FNOs are capable of accurately predicting the evolution of experimental velocity fields throughout the range of Reynolds numbers tested (L2 norm error < 0.1) despite being provided with limited and imperfect flow observations. Given these results, we conclude that this method holds significant potential for real-time predictive flow control of physical systems.", "date": "2023-03-16", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20230316-153752294", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230316-153752294", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "Bren Professor of Computing and Mathematical Sciences" }, { "agency": "Kortschak Scholars Program" }, { "agency": "PIMCO" }, { "agency": "Amazon AI4Science Fellowship" }, { "agency": "Center for Autonomous Systems and Technologies" } ] }, "local_group": { "items": [ { "id": "GALCIT" }, { "id": "Center-for-Autonomous-Systems-and-Technologies-(CAST)" } ] }, "primary_object": { "basename": "2301.08290.pdf", "url": "https://authors.library.caltech.edu/records/1ya2r-9a428/files/2301.08290.pdf" }, "resource_type": "monograph", "pub_year": "2023", "author_list": "Renn, Peter I; Wang, Cong; et el." }, { "id": "https://authors.library.caltech.edu/records/7mzhk-7mq12", "eprint_id": 100934, "eprint_status": "archive", "datestamp": "2023-08-19 23:47:01", "lastmod": "2023-10-19 22:15:38", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kim-Daegyoum", "name": { "family": "Kim", "given": "Daegyoum" } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "Morteza" }, "orcid": "0000-0003-0754-4193" } ] }, "title": "3D vortex formation of rigid and flexible plates in impulsively starting motion", "ispublished": "unpub", "full_text_status": "public", "note": "Submitted - 0810.1962.pdf
", "abstract": "This fluid dynamics video shows three-dimensional vortex formation process for plates in impulsive motion which is investigated experimentally by using defocusing digital particle image velocimetry (DDPIV). Rigid and flexible plate cases are compared in order to study the effect of flexibility on 3D vortex formation and associated hydrodynamic forces. This study was motivated by the general question of how the flexibility of flapping propulsors in flying and swimming animals affects vortex formation and propulsive force. For translating and rotating motion, the flexible plate generates a vortex morphology which is drastically different from that of the rigid plate. We identified the deflection of the tip region as the source of this difference. The flexible plate does not produce a large peak for the hydrodynamic force at the impulsive start and stop. This force trend is correlated with smooth vortex formation and shedding processes.", "date": "2020-01-28", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20200127-092211377", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200127-092211377", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.48550/arXiv.0810.1962", "primary_object": { "basename": "0810.1962.pdf", "url": "https://authors.library.caltech.edu/records/7mzhk-7mq12/files/0810.1962.pdf" }, "resource_type": "monograph", "pub_year": "2020", "author_list": "Kim, Daegyoum and Gharib, Morteza" }, { "id": "https://authors.library.caltech.edu/records/jmp5t-m2a91", "eprint_id": 100917, "eprint_status": "archive", "datestamp": "2023-08-19 04:03:48", "lastmod": "2023-10-19 22:14:40", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Aria-A-I", "name": { "family": "Aria", "given": "Adrianus I." } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "Morteza" }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Bouncing Water Droplet on a Superhydrophobic Carbon Nanotube Array", "ispublished": "unpub", "full_text_status": "public", "note": "This work was supported by The Charyk Foundation and The Fletcher\nJones Foundation.\n\nSubmitted - 1010.1351.pdf
", "abstract": "Over the past few decades, superhydrophobic materials have attaracted a lot of interests, due to their numerous practical applications. Among various superhydrophobic materials, carbon nanotube arrays have gained enormous attentions simply because of their outstanding properties. The impact dynamic of water droplet on a superhydrophobic carbon nanotube array is shown in this fluid dynamics video.", "date": "2020-01-25", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20200124-153805302", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200124-153805302", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Charyk Foundation" }, { "agency": "Fletcher Jones Foundation" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.48550/arXiv.1010.1351", "primary_object": { "basename": "1010.1351.pdf", "url": "https://authors.library.caltech.edu/records/jmp5t-m2a91/files/1010.1351.pdf" }, "resource_type": "monograph", "pub_year": "2020", "author_list": "Aria, Adrianus I. and Gharib, Morteza" }, { "id": "https://authors.library.caltech.edu/records/n0hkg-rdb29", "eprint_id": 100915, "eprint_status": "archive", "datestamp": "2023-08-19 21:54:11", "lastmod": "2023-10-19 22:14:34", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hirsch-D", "name": { "family": "Hirsch", "given": "D." } }, { "id": "Graff-E-C", "name": { "family": "Graff", "given": "E. C." } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Compressible Flows in Fluidic Oscillators", "ispublished": "unpub", "full_text_status": "public", "note": "Submitted - 1310.3310.pdf
", "abstract": "We present qualitative observations on the internal flow characteristics of fluidic oscillator geometries commonly referred to as sweeping jets in active flow control applications. This is part of the fluid dynamics videos.", "date": "2020-01-25", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20200124-153014445", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200124-153014445", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.48550/arXiv.1310.3310", "primary_object": { "basename": "1310.3310.pdf", "url": "https://authors.library.caltech.edu/records/n0hkg-rdb29/files/1310.3310.pdf" }, "resource_type": "monograph", "pub_year": "2020", "author_list": "Hirsch, D.; Graff, E. C.; et el." }, { "id": "https://authors.library.caltech.edu/records/tgdfe-8b591", "eprint_id": 79421, "eprint_status": "archive", "datestamp": "2023-08-19 18:00:44", "lastmod": "2024-01-13 20:36:45", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" }, { "id": "Roshko-A", "name": { "family": "Roshko", "given": "A." } }, { "id": "Sarohia-V", "name": { "family": "Sarohia", "given": "V." } } ] }, "title": "Effect of Flow Oscillations on Cavity Drag and a Technique for Their Control", "ispublished": "unpub", "full_text_status": "public", "note": "The research described in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, and was sponsored by the U.S. Army Research Office and the National Aeronautics and Space Administration.\n\nReference herein to any specific commercial product, process, or service by trade name, trade mark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government, or the Jet Propulsion Laboratory, California Institute of Technology.\n\nThe view, opinions, and/or findings contained in this report are those of the authors and should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other documentation.\n\nThis effort presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, Contract NAS7-918 and sponsored by the U.S. Army Research Office, Contract No. 17134E.\n\nWe are indebted to Drs. Luis Bernal, for his assistance during the difficult LDV measurement phase, and Dan Nosenchuck, for his assistance during the early strip-heater experiments. Thanks are also due to the technical staff of the Fluid Dynamics Group at JPL, especially to chief technician, Mr. Wayne Bixler, and Messrs. Barney Green, Stan Kikkert, and Robert Smither for their excellent\nworkmanship and assistance in construction of the experimental apparatus.\n\nPublished - 19860012048.pdf
", "abstract": "The phenomenon of cavity flow oscillation is investigated to determine the conditions for onset of periodic oscillations and to understand the relationship between the state of the shear layer and the cavity drag. Experiments have been performed in a water tunnel using a 4\" axisymmetric cavity model instrumented with a strip heater on the nose cone and pressure taps in and around the cavity. A complete set of measurements of oscillation phase, amplitude amplification along the flow direction, distribution of shear stress and other momentum flux is obtained by means of a laser Doppler velocimeter. Drag\nmeasurements were made by integrating the mean pressure over the solid surfaces of the cavity. Results indicated exponential cavity drag dependence on the length of the cavity. A jump in the cavity drag coefficient is observed as the cavity flow shows a bluff body wake type behavior. An independent estimate of the drag, which is obtained by integration of shear and mean momentum transfer terms over the peripheral area of the cavity, confirms the exponential dependence of drag on the length of the cavity. Results, also reveal that the drag of the cavity in the non-oscillating mode is less than the case if the cavity were\nreplaced by a solid surface. Natural and forced oscillations of the cavity shear layer spanning the gap are studied. The forced oscillations are introduced by a\nsinusoidally heated thin-film strip which excites the Tollmein-Schlichting waves in the boundary layer upstream of the gap. For a sufficiently large gap, self-sustained\nperiodic oscillations are observed, while for smaller gaps, which do not oscillate naturally, periodic oscillations can be obtained by external forcing through the strip heater. In the latter case resonance is observed whenever the\nforcing frequency satisfies phase criterion \u03c8/2\u03c0 = N, and amplitude exceeds certain threshold levels, but the phenomenon, is non-self-supporting. The drag of the cavity can be increased by one order of magnitude in the non-oscillating case through external forcing. For naturally occurring oscillations, it is possible for two waves to co-exist in the shear layer (natural and forced). Also, it is possible to completely eliminate mode switching by applying external forcing. For the first time a test is performed to cancel or dampen the amplitude of Kelvin-Helmholtz wave in the cavity shear layer. This is done through introducing an\nexternal perturbation with the same frequency of the natural component but having a different phase. Reduction by a factor of 2 is obtained in the amplitude of the oscillation.", "date": "2017-07-26", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170726-123311179", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170726-123311179", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "NAS7-918" }, { "agency": "Army Research Office (ARO)", "grant_number": "17134E" } ] }, "other_numbering_system": { "items": [ { "id": "85-72", "name": "JPL Publication" } ] }, "primary_object": { "basename": "19860012048.pdf", "url": "https://authors.library.caltech.edu/records/tgdfe-8b591/files/19860012048.pdf" }, "resource_type": "monograph", "pub_year": "2017", "author_list": "Gharib, M.; Roshko, A.; et el." }, { "id": "https://authors.library.caltech.edu/records/ktra4-sre83", "eprint_id": 41438, "eprint_status": "archive", "datestamp": "2023-08-19 21:26:59", "lastmod": "2024-01-13 06:04:13", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Williams-Stuber-K", "name": { "family": "Williams-Stuber", "given": "K." } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Study of the origin of three dimensional structures and chaos in an externally forced free shear layer", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1989 by K. Williams-Stuber and M. Gharib. Published by the American Institute of Aeronautics and\nAstronautics, Inc. with permission.\n\nThe work presented here was sponsored by AFOSR under contract number AFOSR-87-0330.\n\nPublished - Gharib_1989p89-1021.pdf
", "abstract": "Experiments on an externally forced free shear layer are performed which study the origin of three-dimensional structures\nand chaos in shear flows. Transition routes between the laminar two-dimensional stages of shear flows and their final\ncomplex three-dimensional stages are examined. Two avenues of investigation are pursued. First, the general idea of a\nmulti-frequency route to chaos is examined which treats the shear flow as an open dynamical system. An attempt is\nmade to apply concepts from nonlinear dynamics to these systems. Secondly, a new approach to generating three-dimensional\nstructures in shear flows which involves the creation of a spatial shear in the frequency of external\nperturbations is presented. In these experiments, a variety of vortex reconnection behaviors is observed at the\ndiscontinuity.", "date": "1989-03", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20130920-095600412", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130920-095600412", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "AFOSR-87-0330" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1989-1021", "primary_object": { "basename": "Gharib_1989p89-1021.pdf", "url": "https://authors.library.caltech.edu/records/ktra4-sre83/files/Gharib_1989p89-1021.pdf" }, "resource_type": "monograph", "pub_year": "1989", "author_list": "Williams-Stuber, K. and Gharib, M." }, { "id": "https://authors.library.caltech.edu/records/pmmf3-3e712", "eprint_id": 41437, "eprint_status": "archive", "datestamp": "2023-08-19 20:42:26", "lastmod": "2024-01-13 06:04:11", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Stuber-K", "name": { "family": "Stuber", "given": "K." } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Experiments on the Forced Wake of an Airfoil", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1988 by Katherine W. Stuber\nPublished by the American Institute of Aeronautics and\nAstronautics, Inc. with permission.\n\nThis paper is based on the work from the Ph.D. Thesis of\nK. Stuber which was carried out at the University of California,\nSan Diego. The work was sponsored by the Defense Advanced\nResearch Projects Agency - Applied and Computational\nMathematics Program through the University Research Initiative\nprogram under contract number DARPA/ONR N00014-86K-0758.\n\nPublished - Gharib_1988p723.pdf
", "abstract": "Presented here is an experimental effort which attempts to\nunderstand the nature of the wake of an airfoil in a controlled\nenvironment. The frequency of oscillation in the wake (the vortex\nshedding frequency) is controlled through the introduction\nof an external perturbation. Strip heaters are used to introduce\nwaves into the top and bottom boundary layers of a thin symmetric\nairfoil which are amplified and introduced to the wake.\nThe linear and nonlinear interactions of these waves in the wake\nare studied in detail. Three modes of interaction have been\nobserved through flow visualization and velocity measurements:\nfrequency locking in which the vortex shedding frequency is the\nsame as the forcing frequency, quasiperiodic vortex interaction\nin which periodic clusters of vortices are observed in the wake,\nand chaotic vortex interaction in which the vortices in the wake\nhave a three dimensional random structure.", "date": "1988-07", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20130920-090200765", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130920-090200765", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "DARPA/URI", "grant_number": "N00014-86K-0758" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1988-3840", "primary_object": { "basename": "Gharib_1988p723.pdf", "url": "https://authors.library.caltech.edu/records/pmmf3-3e712/files/Gharib_1988p723.pdf" }, "resource_type": "monograph", "pub_year": "1988", "author_list": "Stuber, K. and Gharib, M." }, { "id": "https://authors.library.caltech.edu/records/547qy-g0t94", "eprint_id": 41870, "eprint_status": "archive", "datestamp": "2023-08-19 20:03:33", "lastmod": "2024-01-13 06:04:38", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" }, { "id": "Willert-C", "name": { "family": "Willert", "given": "C." }, "orcid": "0000-0002-1668-0181" } ] }, "title": "Particle Tracing: Revisited", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1988 by Morteza Gharib.\nPublished by the American Institute of Aeronautics and Astronautics, Inc.\nAn initiation grant from the Engineering Foundation (GR Engng Fdn RI-A-86-7) has been instrumental in the development of the\nautomatic particle tracing technique described in this paper.\nCurrently a grant from DARPA/ACMP is supporting us in\nefforts to add the three-dimensional and multifield capability to\nthe technique. Many colleagues and former students have\nhelped us in bringing the technique to its present stage. We\nwould like to thank Dr. Miguel Hernan for helping with the\ninitial development of the idea, Barry Dyne and Oran Thomas\nfor helping in the development of software, Thomas Phillips and\nChee Yap for different stages of hardware development and Dr.\nKathie Stuber for her careful laser doppler measurements.\n\nPublished - Gharib_1988p1935.pdf
", "abstract": "Particle tracing is a simple technique used to infer global quantitative\ninformation regarding velocity and vorticity fields from\nflow images. In this paper, recent advances in solving major\ndrawbacks associated with conventional particle tracing are discussed.\nA quantitative automatic scheme which eliminates the\nphotographic step and is capable of constructing the velocity\nfield directly from the experimental set up is presented.", "date": "1988", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20131010-131031641", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131010-131031641", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Engineering Foundation", "grant_number": "RI-A-86-7" }, { "agency": "DARPA/ACMP" } ] }, "other_numbering_system": { "items": [ { "id": "88-3776-CP", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "Gharib_1988p1935.pdf", "url": "https://authors.library.caltech.edu/records/547qy-g0t94/files/Gharib_1988p1935.pdf" }, "resource_type": "monograph", "pub_year": "1988", "author_list": "Gharib, M. and Willert, C." }, { "id": "https://authors.library.caltech.edu/records/5n8jp-1a011", "eprint_id": 41413, "eprint_status": "archive", "datestamp": "2023-08-19 19:35:43", "lastmod": "2024-01-13 06:04:07", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Aref-H", "name": { "family": "Aref", "given": "H." } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" }, { "id": "Van-Atta-C-W", "name": { "family": "Van Atta", "given": "C. W." } } ] }, "title": "Chaos in Shear Flows", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1987 American Institute Aeronautics and\nAstronautics, Inc.\n\nOur principal collaborators in the investigations reported here are B. Eckhardt, M. Hammache, S. W. Jones, and K. Stuber. This work is supported by AMCP at DARPA.\n\nPublished - Gharib_1987p87-1251.pdf
", "abstract": "Almost 25 years ago Lorenz published his seminal\nstudy on the existence of a strange attractor in the phase\nspace of a severely truncated model system arising from\nthe hydrodynamical equations describing two-dimensional\nconvection. Nearly a century ago Poincare\npublished his famous treatise Les Methodes Noovelles\nde la Mecaniaue Celeste (1892) in which the possible\ncomplexity of behavior in nonintegrable, conservative\nsystems was first envisioned. Both these works address\nan age old puzzle: How do apparently stochastic outputs\narise from an entirely deterministic system subject to\nnon-stochastic inputs?", "date": "1987-06", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20130919-121228655", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130919-121228655", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1987-1251", "primary_object": { "basename": "Gharib_1987p87-1251.pdf", "url": "https://authors.library.caltech.edu/records/5n8jp-1a011/files/Gharib_1987p87-1251.pdf" }, "resource_type": "monograph", "pub_year": "1987", "author_list": "Aref, H.; Gharib, M.; et el." }, { "id": "https://authors.library.caltech.edu/records/rfchn-epp30", "eprint_id": 41306, "eprint_status": "archive", "datestamp": "2023-08-19 18:19:02", "lastmod": "2024-01-13 06:04:03", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Aaron-K-M", "name": { "family": "Aaron", "given": "K. M." } }, { "id": "Hernan-M-A", "name": { "family": "Hernan", "given": "M. A." } }, { "id": "Parikh-P", "name": { "family": "Parikh", "given": "P." } }, { "id": "Sarohia-V", "name": { "family": "Sarohia", "given": "V." } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Simulation and Analysis of Natural Rain in a Wind Tunnel via Digital Image Processing Techniques", "ispublished": "unpub", "full_text_status": "public", "note": "This paper is declared a work of the U.S.\nGovernment and therefore is in the public domain.\n\nThis work was carried out at the Jet Propulsion Laboratory, California Institute of Technology\nunder Contract NAS7-918, Task Order RE 65/Amendment\n459, jointly funded by NASA Langley Research\nCenter and Goddard Space Flight Center - Wallops\nFlight Facility (505-45-00-04-59). \nThe authors extend their gratitude to Mr.\nEarl Dunham Jr., NASA Langley Research Center, and\nMr. Edward Melson, NASA Wallops Flight Facility\nfor many valuable technical suggestions throughout\nthe program. The assistance of Mr. R. Smither, \nMr. W. Bixler and Mr. S. Kikkert in the design and\nfabrication of the experimental facilities and in\nacquisition of the data is greatly appreciated.\n\nPublished - Gharib_1986p86-0291.pdf
", "abstract": "It is desired to simulate natural rain in a\nwind tunnel in order to investigate its influence\non the aerodynamic characteristics of aircraft.\nRain simulation nozzles have been developed and\ntested at JPL. Pulsed laser sheet illumination is\nused to photograph the droplets in the moving\nairstream. Digital image processing techniques are\napplied to these photographs for calculation of\nrain statistics to evaluate the performance of the\nnozzles. It is found that fixed hypodermic type\nnozzles inject too much water to simulate natural\nrain conditions. A modification uses two aerodynamic\nspinners to flex a tube in a pseudo-random\nfashion to distribute the water over a larger area.", "date": "1986-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20130913-080959226", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130913-080959226", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA", "grant_number": "NAS7-918" }, { "agency": "Goddard Space Flight Center", "grant_number": "505-45-00-04-59" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1986-291", "primary_object": { "basename": "Gharib_1986p86-0291.pdf", "url": "https://authors.library.caltech.edu/records/rfchn-epp30/files/Gharib_1986p86-0291.pdf" }, "resource_type": "monograph", "pub_year": "1986", "author_list": "Aaron, K. M.; Hernan, M. A.; et el." }, { "id": "https://authors.library.caltech.edu/records/8m7fj-2vh39", "eprint_id": 41305, "eprint_status": "archive", "datestamp": "2023-08-19 17:38:46", "lastmod": "2024-01-13 06:04:01", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Active Control of Cavity Shear Layer Oscillation", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1985 American Institute of Aeronautics and Astronautics, Inc.\n\nThis paper is based on work from the Ph.D Thesis by the author which was carried out at the Jet Propulsion Laboratory, California Institute of Technology. The work was sponsored by U. S. Army Research Office Contract No. 7134E and National Science Foundation Grant No. CME-7723541.\n\nThe author is grateful for assistance from Professors A. Roshko, H. W. Liepman, D. M. Nosenchuck and Dr. V. Sarohia.\n\nPaper title varies in AIAA Aerospace Research Central database: Response of the cavity shear layer oscillations to external forcing.\n\nPublished - Gharib_1985p85-0528.pdf
", "abstract": "Influence of externally forced initial\nflow conditions on axisymmetric cavity\nshear layer were studied. A sinusoidally\nheated strip upstream of the cavity\nexcited Tollmien-Schlichting waves which,\nafter amplification by the boundary layer,\nwere introduced to the cavity shear layer.\nBy choosing forcing frequencies within the\nrange of shear layer receptivity, it was\npossible to control frequency and\namplitude of the oscillations and\nconsequently control the cavity drag.", "date": "1985-03", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20130913-075811043", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130913-075811043", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)", "grant_number": "7134E" }, { "agency": "NSF", "grant_number": "CME-7723541" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1985-528", "primary_object": { "basename": "Gharib_1985p85-0528.pdf", "url": "https://authors.library.caltech.edu/records/8m7fj-2vh39/files/Gharib_1985p85-0528.pdf" }, "resource_type": "monograph", "pub_year": "1985", "author_list": "Gharib, M." }, { "id": "https://authors.library.caltech.edu/records/9f9xn-qab95", "eprint_id": 41291, "eprint_status": "archive", "datestamp": "2023-08-19 17:30:57", "lastmod": "2024-01-13 06:03:57", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gharib-M", "name": { "family": "Gharib", "given": "M." }, "orcid": "0000-0003-0754-4193" }, { "id": "Hernan-M-A", "name": { "family": "Hernan", "given": "M. A." } }, { "id": "Yavrouian-A-H", "name": { "family": "Yavrouian", "given": "A. H." } }, { "id": "Sarohia-V", "name": { "family": "Sarohia", "given": "V." } } ] }, "title": "Flow Velocity Measurement by Image Processing of Optically Activated Tracers", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1985 AIAA.\n\nThe research described in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, and was sponsored by\nthe National Aeronautics and Space Administration.\nThe authors extend their gratitude to Mr. G. Hicks\nand Mr. R. Graves for their support and valuable\nsuggestions. The authors also thank Messrs. R.\nSmither and T. Wynne for their contributions in\nfabrication, assembly, and conduction of the experiments.\n\nPublished - Gharib_1985p85-0172.pdf
", "abstract": "A computerized flow visualization technique\ncapable of quantifying the flow field automatically\nhas been developed. This technique uses afterglowing effect of optically activated phosphorescent\nparticles to retrieve vectorial information on each\ntrace. By using this information, in conjunction\nwith computer image processing, the flow field of a\nfree surface transient vortex was investigated.", "date": "1985-01", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20130912-112159963", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130912-112159963", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1985-172", "primary_object": { "basename": "Gharib_1985p85-0172.pdf", "url": "https://authors.library.caltech.edu/records/9f9xn-qab95/files/Gharib_1985p85-0172.pdf" }, "resource_type": "monograph", "pub_year": "1985", "author_list": "Gharib, M.; Hernan, M. A.; et el." }, { "id": "https://authors.library.caltech.edu/records/48jjg-car20", "eprint_id": 41304, "eprint_status": "archive", "datestamp": "2023-09-15 04:33:36", "lastmod": "2024-01-13 06:03:59", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dosanjh-Darshan-S", "name": { "family": "Dosanjh", "given": "D. S." } }, { "id": "Matambo-Thompson", "name": { "family": "Matambo", "given": "Thompson" } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "Morteza" }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Supersonic Jet Noise Reduction by Coaxial Jets with Coplanar and Staggered Exits", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1979 American Institute of Aeronautics and\nAstronautics, Inc.\n\nOur thanks to Mrs. K. Curtice\nfor the typing of this paper.\n\nPublished - Gharib_1979p79-0672.pdf
", "abstract": "Far-field noise radiated from coaxial cold underexpanded\njet flows issuing from convergent two-nozzle\nconfigurations with coplanar and staggered-exits\nis investigated experimentally. The coaxial\njets are operated in the \"inverted\" mode, i.e., the\nouter (annular) jet flow Mach number is higher than\nthat of the inner (round) jet. Keeping all other\ngeometrical and operating conditions the same, the\nexit-stagger of the inner (round) and the outer\n(annular) nozzles was varied. It is shown that the\nextent of the exit-stagger affects both the flows\nand the radiated noise from such coaxial underexpanded\njet flows and that comparatively, the lowest\nnoise levels are achieved when the coaxial nozzle-exits\nare coplanar. Moreover, the effectiveness\nof the co-flowing inner jet flow in reducing the\nnoise radiated from either the annular or the coaxial\nunderexpanded jet flows decreases noticeably\nas the exit-stagger is increased.", "date": "1979-03", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20130913-074732862", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130913-074732862", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1979-672", "primary_object": { "basename": "Gharib_1979p79-0672.pdf", "url": "https://authors.library.caltech.edu/records/48jjg-car20/files/Gharib_1979p79-0672.pdf" }, "resource_type": "monograph", "pub_year": "1979", "author_list": "Dosanjh, D. S.; Matambo, Thompson; et el." } ]