Book Section records
https://feeds.library.caltech.edu/people/Rowley-C-W/book_section.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 14:13:13 +0000Computation of Sound Generation and Flow/Acoustic Instabilities in the Flow Past an Open Cavity
https://resolver.caltech.edu/CaltechAUTHORS:20190726-104730500
Authors: {'items': [{'id': 'Colonius-T', 'name': {'family': 'Colonius', 'given': 'Tim'}, 'orcid': '0000-0003-0326-3909'}, {'id': 'Basu-A-J', 'name': {'family': 'Basu', 'given': 'Amit J.'}}, {'id': 'Rowley-C-W', 'name': {'family': 'Rowley', 'given': 'Clarence W.'}, 'orcid': '0000-0002-9099-5739'}]}
Year: 1999
The modes of oscillation and radiated acoustic fields of compressible flows over open cavities are investigated computationally. The compressible Navier-Stokes equations are solved directly (no turbulence model) for two dimensional open cavities with laminar boundary layers upstream. The computational domain is large enough to directly resolve a portion of the radiated acoustic field. The results show a bifurcation from a shear layer mode, for shorter cavities and lower Mach numbers, to a wake mode for longer cavities and higher Mach numbers. The shear layer mode is well characterized by Rossiter modes and these oscillations lead to intense upstream acoustic radiation dominated by a single frequency. The wake mode is characterized instead by a large-scale vortex shedding with Strouhal number nearly independent the Mach number. The vortex shedding causes the boundary layer to periodically separate upstream of the cavity. Acoustic radiation is more intense, with multiple frequencies present. The wake mode oscillation is similar to that reported by Gharib & Roshko (1987) for incompressible cavity flows with laminar upstream boundary layers.https://authors.library.caltech.edu/records/emfpy-s6r46Variational integrators for degenerate Lagrangians, with application to point vortices
https://resolver.caltech.edu/CaltechAUTHORS:20101007-083427136
Authors: {'items': [{'id': 'Rowley-C-W', 'name': {'family': 'Rowley', 'given': 'Clarence W.'}, 'orcid': '0000-0002-9099-5739'}, {'id': 'Marsden-J-E', 'name': {'family': 'Marsden', 'given': 'Jerrold E.'}}]}
Year: 2002
DOI: 10.1109/CDC.2002.1184735
We develop discrete mechanics and variational integrators
for a class of degenerate Lagrangian systems,
and apply these integrators to a system of
point vortices. Excellent numerical behavior is observed.
A longer term goal is to use these integration
methods in the context of control of mechanical
systems, such as coordinated groups of underwater
vehicles. In fact, numerical evidence given
in related problems, such as those in [2] shows that
in the presence of external forces, these methods
give superior predictions of energy behavior.https://authors.library.caltech.edu/records/fq9h3-fhc45On the choice of norm for modeling compressible flow dynamics at reduced-order using the POD
https://resolver.caltech.edu/CaltechAUTHORS:20190214-123721078
Authors: {'items': [{'id': 'Colonius-T', 'name': {'family': 'Colonius', 'given': 'Tim'}, 'orcid': '0000-0003-0326-3909'}, {'id': 'Rowley-C-W', 'name': {'family': 'Rowley', 'given': 'Clancy W.'}, 'orcid': '0000-0002-9099-5739'}, {'id': 'Freund-J-B', 'name': {'family': 'Freund', 'given': 'Jonathan B.'}}, {'id': 'Murray-R-M', 'name': {'family': 'Murray', 'given': 'Richard M.'}, 'orcid': '0000-0002-5785-7481'}]}
Year: 2002
DOI: 10.1109/CDC.2002.1184376
We use POD (proper orthogonal decomposition)/Galerkin projection to investigate and derive reduced-order models of the dynamics of compressible flows. We examine DNS data for two flows, a turbulent M=0.9 jet and self-sustained oscillations in the flow over an open cavity, and show how different choices of norm lead to different definitions of the energetic structures, and, for the cavity, to different reduced-order models of the dynamics. For the jet, we show that the near-field dynamics are fairly well represented by relatively few modes, but that key processes of interest, such as acoustic radiation, are not well captured by norms that are defined based on volume integrals of pressure and velocity. For the cavity flow, we demonstrate that vector-valued POD modes lead to reduced-order models that are much more effective (accurate and stable) than scalar-valued modes defined independently for different flow variables.https://authors.library.caltech.edu/records/w3btx-2kq60Lock-On to a High-Lift State with Oscillatory Forcing in a Three-Dimensional Wake Flow
https://resolver.caltech.edu/CaltechAUTHORS:20190214-083422063
Authors: {'items': [{'id': 'Taira-Kunihiko', 'name': {'family': 'Taira', 'given': 'Kunihiko'}, 'orcid': '0000-0002-3762-8075'}, {'id': 'Rowley-C-W', 'name': {'family': 'Rowley', 'given': 'Clarence W.'}, 'orcid': '0000-0002-9099-5739'}, {'id': 'Colonius-T', 'name': {'family': 'Colonius', 'given': 'Tim'}, 'orcid': '0000-0003-0326-3909'}]}
Year: 2010
DOI: 10.1007/978-3-642-11735-0_6
Flow control is applied to a three-dimensional post-stall flow around a rectangular low-aspect-ratio wing. Steady actuation is used to examine effective flow control setups that modify the vortex dynamics in the wake and achieve increase in lift. For one of the setups, oscillatory forcing is then used to examine the influence of actuation frequency. It is found that sinusoidal actuation requires less momentum to the flow field to achieve lift increase compared to steady momentum injection. There are two observed ranges of forcing frequency at which the flow locks onto period-one and period-two high-lift states. Discussions of the ongoing work on stabilizing separated flow about these periodic high-lift states are offered.https://authors.library.caltech.edu/records/h606f-x2q76