The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Alex Povitsky - One of the best experts on this subject based on the ideXlab platform.
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Sound generation by a street of vortices in a Nonuniform Flow
Physics of Fluids, 2007Co-Authors: Ting-hui Zheng, Georgios H. Vatistas, Alex PovitskyAbstract:Propagation of acoustic waves originating from periodic vortices deforming in a Nonuniform Flow about a rigid body is examined numerically using a high-order compact finite-difference approximation. The governing equations are approximated by the linearized Euler equations in terms of disturbances. The aim of the study is to determine the sound directivity and strength as a result of the vortex street interaction with a solid body under subsonic base Flow conditions. Both the vortex core diameter and vortex street spacing have a minor influence on the amplitude of the produced sound wave. When low-frequency vortex streets interact with a cylinder, the produced sound waves are very different from those that originated from high-frequency vortex streets. The interaction mechanism, sound generation, and propagation in a Nonuniform Flow are quite different for Taylor and Vatistas’ vortex streets. In the case of a low-frequency Vatistas vortex street, the root-mean-square (RMS) value of the acoustic pressure h...
Ting-hui Zheng - One of the best experts on this subject based on the ideXlab platform.
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Sound generation by a street of vortices in a Nonuniform Flow
Physics of Fluids, 2007Co-Authors: Ting-hui Zheng, Georgios H. Vatistas, Alex PovitskyAbstract:Propagation of acoustic waves originating from periodic vortices deforming in a Nonuniform Flow about a rigid body is examined numerically using a high-order compact finite-difference approximation. The governing equations are approximated by the linearized Euler equations in terms of disturbances. The aim of the study is to determine the sound directivity and strength as a result of the vortex street interaction with a solid body under subsonic base Flow conditions. Both the vortex core diameter and vortex street spacing have a minor influence on the amplitude of the produced sound wave. When low-frequency vortex streets interact with a cylinder, the produced sound waves are very different from those that originated from high-frequency vortex streets. The interaction mechanism, sound generation, and propagation in a Nonuniform Flow are quite different for Taylor and Vatistas’ vortex streets. In the case of a low-frequency Vatistas vortex street, the root-mean-square (RMS) value of the acoustic pressure h...
John G. Tsavalas - One of the best experts on this subject based on the ideXlab platform.
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A Column Design for Reducing Viscous Fingering in Size Exclusion Chromatography
Biotechnology Progress, 1996Co-Authors: Erik J. Fernandez, T. Tucker Norton, William C. Jung, John G. TsavalasAbstract:Under high concentration overload conditions, resolution during size exclusion chromatography of proteins can be compromised due to Nonuniform Flow caused by the viscous fingering Flow instability. In this work, the Nonuniform Flow under these chromatographic conditions is analyzed by numerical simulation and magnetic resonance imaging. On the basis of an improved understanding of the Flow phenomena, a new column design is proposed. The effectiveness of the design is evaluated by chromatography, magnetic resonance imaging, and numerical simulation.
Xiao‐dong Tong - One of the best experts on this subject based on the ideXlab platform.
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Polydisperse model for the hydrodynamics of expanded‐bed adsorption systems
Aiche Journal, 2003Co-Authors: Xiao‐dong TongAbstract:A polydisperse model is established to describe the hydrodynamic behaviors of solid particles within an expanded-bed adsorption column. This model has been used to simulate bed expansions conducted by different researchers under various operating conditions, and good agreements are found between the experimental and simulated results. The model is effective in simulating not only the change of bed height with fluid velocity, but also the size distributions of solid particles at different axial positions. Due to Nonuniform Flow in the column and density distribution of the particles, the calculated bed voidage is somewhat different from the measured one for the bottom and top regions of the column.
Yu M Glyavin - One of the best experts on this subject based on the ideXlab platform.
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measurement of plasma density in the discharge maintained in a Nonuniform gas Flow by a high power terahertz wave gyrotron
Physics of Plasmas, 2016Co-Authors: A V Sidorov, S V Razin, S V Golubev, M I Safronova, A P Fokin, A G Luchinin, A V Vodopyanov, Yu M GlyavinAbstract:We performed measurements of plasma density in a “point-like” discharge, which is generated in a Nonuniform Flow of a gas (argon) under the action of high-power terahertz gyrotron radiation with a frequency of 0.67 THz, a power of 40 kW, and a pulse duration of 20 μs. The Nonuniform Flow was produced by injecting the gas to the vacuum chamber through a small hole (0.14 mm in diameter) under a background pressure at a level of 0.01 Torr. The discharge developed and was localized only in a small region of space (about 1 mm) near the gas injection hole, where the pressure was high (close to the atmospheric one) and the breakdown conditions (the “point-like” discharge) were fulfilled. The density of electrons in the discharge was measured by observing the Stark broadening of the atomic radiation line Hα of hydrogen (656.3 nm) which was present in the discharge as a minor admixture. The plasma density in the discharge was equal to about 2 × 1016 cm−3, which exceeds the cut-off density for a frequency of 0.67 T...
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Measurement of plasma density in the discharge maintained in a Nonuniform gas Flow by a powerful radiation of terahertz-band gyrotron
2016 41st International Conference on Infrared Millimeter and Terahertz waves (IRMMW-THz), 2016Co-Authors: A V Sidorov, S V Razin, S V Golubev, M I Safronova, A P Fokin, A G Luchinin, A V Vodopyanov, Yu M GlyavinAbstract:We performed measurements of plasma density in a “point-like” discharge, which is generated in a Nonuniform Flow of a gas (argon) under the action of high-power terahertz gyrotron radiation with a frequency of 0.67 THz, a power of 40 kW, and a pulse duration of 20 μs. The Nonuniform Flow was produced by injecting the gas to the vacuum chamber through a small hole (0.14 mm in diameter) under a background pressure at a level of 0.01 Torr. The discharge developed and was localized only in a small region of space (about 1 mm) near the gas injection hole, where the pressure was high (close to the atmospheric one) and the breakdown conditions (the “point-like” discharge) were fulfilled. The density of electrons in the discharge was measured by observing the Stark broadening of the atomic radiation line Ha of hydrogen (656.3 nm) which was present in the discharge as a minor admixture. The plasma density in the discharge was equal to about 2·1016 cm-3, which exceeds the value being critical for a frequency of 0.67 THz used to maintain the radiation discharge.
