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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenSat, 13 Apr 2024 02:04:45 +0000Measured distortion of a laminar circular Couette flow by end effects
https://resolver.caltech.edu/CaltechAUTHORS:20130509-154835368
Authors: {'items': [{'id': 'Coles-D-E', 'name': {'family': 'Coles', 'given': 'D.'}}, {'id': 'Van-Atta-C-W', 'name': {'family': 'Van Atta', 'given': 'C.'}}]}
Year: 1966
DOI: 10.1017/S0022112066000223
Measurements at moderately large Reynolds numbers in a finite laminar circular Couette flow show that the tangential motion near the axial plane of symmetry is two-dimensional, within experimental accuracy, but is nevertheless strongly modified by end conditions.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/r5jxf-m3270Digital Experiment in Spiral Turbulence
https://resolver.caltech.edu/CaltechAUTHORS:20120905-104410957
Authors: {'items': [{'id': 'Coles-D-E', 'name': {'family': 'Coles', 'given': 'D.'}}, {'id': 'Van-Atta-C-W', 'name': {'family': 'Van Atta', 'given': 'C. W.'}}]}
Year: 1967
DOI: 10.1063/1.1762428
Digital measurements in a stationary mixed laminar‐turbulent flow show that the turbulent region is highly inhomogeneous and that the mean flow is highly three‐dimensional.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sndsk-5z465Ordered and chaotic vortex streets behind circular cylinders at low Reynolds numbers
https://resolver.caltech.edu/CaltechAUTHORS:20130916-160630938
Authors: {'items': [{'id': 'Van-Atta-C-W', 'name': {'family': 'Van Atta', 'given': 'C. W.'}}, {'id': 'Gharib-M', 'name': {'family': 'Gharib', 'given': 'M.'}}]}
Year: 1987
DOI: 10.1017/S0022112087000065
We report some experiments undertaken to investigate the origin of ordered and chaotic laminar vortex streets behind circular cylinders at low Reynolds numbers. We made simultaneous measurements of near wake longitudinal velocity and cylinder lateral vibration amplitude spectra for cylinder Reynolds numbers in the range from 40 to 160. For a non-vibrating cylinder the velocity energy spectra contained only a single peak, at the Strouhal frequency. When the cylinder was observed to vibrate in response to forcing by the vortex wake, additional dominant spectral peaks appeared in the resulting 'ordered' velocity spectra. Cylinder vibrations too small to be noticed with the naked eye or from audible Aeolian tones produced a coupled wake-cylinder response with dramatic effects in hot-wire and cylinder vibration detector signals. The velocity spectra associated with these coupled motions had dominant peaks at the Strouhal frequency fs, at a frequency fc proportional to the fundamental cylinder vibration frequency, and at sum and difference combinations of multiples of fs and fc. In windows of chaos the velocity spectra were broadened by switching between different competing coupling modes. The velocity spectra were very sensitive to the nature of the boundary conditions at the ends of the cylinder. Our measurements strongly suggest that the very similar regions of 'order' and 'chaos' observed by Sreenivasan and interpreted by him as transition through quasi-periodic states in the sense of the Ruelle, Takens, and Newhouse theory were also due to aeroelastic coupling of the vortex wake with cylinder vibration modes.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0qc4b-rnc41Chaos in Shear Flows
https://resolver.caltech.edu/CaltechAUTHORS:20130919-121228655
Authors: {'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.'}}]}
Year: 1987
DOI: 10.2514/6.1987-1251
Almost 25 years ago Lorenz published his seminal
study on the existence of a strange attractor in the phase
space of a severely truncated model system arising from
the hydrodynamical equations describing two-dimensional
convection. Nearly a century ago Poincare
published his famous treatise Les Methodes Noovelles
de la Mecaniaue Celeste (1892) in which the possible
complexity of behavior in nonintegrable, conservative
systems was first envisioned. Both these works address
an age old puzzle: How do apparently stochastic outputs
arise from an entirely deterministic system subject to
non-stochastic inputs?https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5n8jp-1a011Three-dimensional structure of ordered and chaotic vortex streets behind circular cylinders at low Reynolds numbers
https://resolver.caltech.edu/CaltechAUTHORS:20131024-085544182
Authors: {'items': [{'id': 'Van-Atta-C-W', 'name': {'family': 'Van Atta', 'given': 'C. W.'}}, {'id': 'Gharib-M', 'name': {'family': 'Gharib', 'given': 'M.'}}, {'id': 'Hammache-M', 'name': {'family': 'Hammache', 'given': 'M.'}}]}
Year: 1988
We have investigated the spatial and temporal structure of certain cases of chaotic and organized vortex shedding in self-excited cylinder wakes at low Reynolds number (40–200) by extending hot-wire measurements to much larger downstream locations than our earlier measurements (Van Atta and Gharib, 1987) and performing concurrent smoke-wire flow visualizations. We describe here results for two cases in which chaotic vortex shedding is observed. The first is the single-vibration frequency locked-in case, in which the most highly disturbed regions of the vortex street, which produce chaotic spectra, are confined to compact spanwise-periodic propagating disturbed regions. The second is the multiple-vibration frequency case in which chaotic velocity spectra are observed at all spanwise locations.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7j3gq-c3973Bispectral analysis of ordered and chaotic vortex shedding from vibrating cylinders at low Reynolds numbers
https://resolver.caltech.edu/CaltechAUTHORS:20130918-154846323
Authors: {'items': [{'id': 'Elgar-S', 'name': {'family': 'Elgar', 'given': 'Steve'}}, {'id': 'Van-Atta-C-W', 'name': {'family': 'Van Atta', 'given': 'C. W.'}}, {'id': 'Gharib-M', 'name': {'family': 'Gharib', 'given': 'M.'}}]}
Year: 1989
DOI: 10.1016/0167-2789(89)90010-9
Bispectral analysis is used to compare and contrast ordered and chaotic vortex shedding from a cylinder in low-Reynolds-number flow. Auto-bicoherence spectra of the wake velocity field for ordered shedding are characterized by sharp peaks, indicating coupling between fluid motions at the vortex shedding frequency, its side bands, and its harmonics. Wake velocities for chaotic shedding have broad power spectral peaks and substantial low-frequency energy. The corresponding auto-bicoherences show coupling between motions with a relatively wide range of frequencies, especially low frequencies.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hcvth-vbr13Cross-bispectral analysis of a vibrating cylinder and its wake in low Reynolds number flow
https://resolver.caltech.edu/CaltechAUTHORS:20130918-152602618
Authors: {'items': [{'id': 'Elgar-S', 'name': {'family': 'Elgar', 'given': 'Steve'}}, {'id': 'Van-Atta-C-W', 'name': {'family': 'Van Atta', 'given': 'C. W.'}}, {'id': 'Gharib-M', 'name': {'family': 'Gharib', 'given': 'M.'}}]}
Year: 1990
DOI: 10.1016/0889-9746(90)90043-5
Cross-bispectral analysis is used to investigate the coupling between a slender vibrating cylinder and the velocity field in its wake at low Reynolds numbers [Re = O(10^2)]. The velocity field was characterized by a complicated power spectrum, with low frequency peaks as well as upper and lower side band peaks near the primary Strouhal frequency peak and its harmonics. Power spectral and cross-bispectral analyses indicate that the rich structure of the wake velocity power spectra is a direct consequence of the vibrating cylinder. The data suggest the cylinder is coupled to its wake in the sense that the cylinder vibrations introduce motions into the wake at the vibration frequency, and these motions interact nonlinearly within the wake to produce fluctuations at other frequencies. Cross-bispectral analysis isolates the interactions between cylinder vibrations and wake fluctuations.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w2fe1-59982