The Experts below are selected from a list of 43242 Experts worldwide ranked by ideXlab platform
Gary D Doolen - One of the best experts on this subject based on the ideXlab platform.
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lattice boltzmann method on a curvilinear coordinate system vortex shedding behind a circular Cylinder
Physical Review E, 1997Co-Authors: Gary D DoolenAbstract:The interpolation-supplemented lattice Boltzmann equation (ISLBE) method is used to simulate the two-dimensional vortex shedding behind a circular Cylinder at low Reynolds numbers. Simulations are carried out on a polar-coordinate grid system with a dense grid distributed near the Cylinder Surface. The Strouhal number, the drag, and the lift coefficients obtained from the simulations agree well with previous experimental measurements and classical computational fluid dynamics simulations. Comparisons of detailed flow patterns with other studies via streamlines and streaklines are also satisfactory. The ability of the ISLBE scheme to simulate complicated long-term periodic flow phenomena is demonstrated.
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lattice boltzmann method on a curvilinear coordinate system vortex shedding behind a circular Cylinder
Physical Review E, 1997Co-Authors: Gary D DoolenAbstract:The interpolation-supplemented lattice Boltzmann equation (ISLBE) method is used to simulate the two-dimensional vortex shedding behind a circular Cylinder at low Reynolds numbers. Simulations are carried out on a polar-coordinate grid system with a dense grid distributed near the Cylinder Surface. The Strouhal number, the drag, and the lift coefficients obtained from the simulations agree well with previous experimental measurements and classical computational fluid dynamics simulations. Comparisons of detailed flow patterns with other studies via streamlines and streaklines are also satisfactory. The ability of the ISLBE scheme to simulate complicated long-term periodic flow phenomena is demonstrated. {copyright} {ital 1997} {ital The American Physical Society}
Bertrand Audoin - One of the best experts on this subject based on the ideXlab platform.
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the transient response of a transversely isotropic Cylinder under a laser point source impact
Ultrasonics, 2006Co-Authors: Y Pan, Mathieu Perton, C Rossignol, Bertrand AudoinAbstract:The transient response of a transversely isotropic Cylinder under a laser point source impact is solved theoretically. The radial displacement generated by the laser under the ablation regime is numerically calculated by introducing Fourier series expansion and two-dimensional Fourier transform. The validity of this theoretical solution is demonstrated on a fiber reinforced composite Cylinder with a strong anisotropy. Experimental displacements are detected at the Cylinder Surface by the laser ultrasonic technique, and are analyzed by the ray trajectories. Corresponding theoretical displacements are calculated numerically and compared to the experimental signals. Good agreement is found. The diffraction effect caused by the cusp is observed in both theory and experiment.
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acoustic waves generated by a laser point source in an isotropic Cylinder
Journal of the Acoustical Society of America, 2004Co-Authors: Y Pan, C Rossignol, Bertrand AudoinAbstract:The acoustic field of a homogeneous and isotropic Cylinder generated by a laser point source in either ablation or thermoelastic regime is obtained theoretically. A three-dimensional Fourier transform is used to calculate the acoustic displacement at the Cylinder Surface. Experimental waveforms were measured and analyzed for both regimes. Theoretical normal displacements under either regime are calculated and compared to the experimental signals for aluminum Cylinders. Very good agreements are observed in the arrival time, shape, and relative amplitude (i) of the cylindrical Rayleigh waves with different round trips, and (ii) of the various longitudinal and transverse bulk waves propagating through the Cylinder or reflected at the free circular Surface.
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acoustic waves generated by a laser line pulse in a transversely isotropic Cylinder
Applied Physics Letters, 2003Co-Authors: Y Pan, C Rossignol, Bertrand AudoinAbstract:The acoustic field of a homogeneous and transversely isotropic Cylinder generated by a laser line pulse in either ablation or thermoelastic regime is obtained theoretically. A two-dimensional Fourier transform is used to calculate the acoustic displacement at the Cylinder Surface. Experimental and theoretical normal displacements under either regime are obtained and compared for aluminum Cylinders. Very good agreements are observed in the time, shape, and relative amplitude (i) of the cylindrical Rayleigh waves with different roundtrips and (ii) of the various longitudinal and transverse bulk waves propagating through the Cylinder or reflected at the free circular Surface.
Y Pan - One of the best experts on this subject based on the ideXlab platform.
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the transient response of a transversely isotropic Cylinder under a laser point source impact
Ultrasonics, 2006Co-Authors: Y Pan, Mathieu Perton, C Rossignol, Bertrand AudoinAbstract:The transient response of a transversely isotropic Cylinder under a laser point source impact is solved theoretically. The radial displacement generated by the laser under the ablation regime is numerically calculated by introducing Fourier series expansion and two-dimensional Fourier transform. The validity of this theoretical solution is demonstrated on a fiber reinforced composite Cylinder with a strong anisotropy. Experimental displacements are detected at the Cylinder Surface by the laser ultrasonic technique, and are analyzed by the ray trajectories. Corresponding theoretical displacements are calculated numerically and compared to the experimental signals. Good agreement is found. The diffraction effect caused by the cusp is observed in both theory and experiment.
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acoustic waves generated by a laser point source in an isotropic Cylinder
Journal of the Acoustical Society of America, 2004Co-Authors: Y Pan, C Rossignol, Bertrand AudoinAbstract:The acoustic field of a homogeneous and isotropic Cylinder generated by a laser point source in either ablation or thermoelastic regime is obtained theoretically. A three-dimensional Fourier transform is used to calculate the acoustic displacement at the Cylinder Surface. Experimental waveforms were measured and analyzed for both regimes. Theoretical normal displacements under either regime are calculated and compared to the experimental signals for aluminum Cylinders. Very good agreements are observed in the arrival time, shape, and relative amplitude (i) of the cylindrical Rayleigh waves with different round trips, and (ii) of the various longitudinal and transverse bulk waves propagating through the Cylinder or reflected at the free circular Surface.
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acoustic waves generated by a laser line pulse in a transversely isotropic Cylinder
Applied Physics Letters, 2003Co-Authors: Y Pan, C Rossignol, Bertrand AudoinAbstract:The acoustic field of a homogeneous and transversely isotropic Cylinder generated by a laser line pulse in either ablation or thermoelastic regime is obtained theoretically. A two-dimensional Fourier transform is used to calculate the acoustic displacement at the Cylinder Surface. Experimental and theoretical normal displacements under either regime are obtained and compared for aluminum Cylinders. Very good agreements are observed in the time, shape, and relative amplitude (i) of the cylindrical Rayleigh waves with different roundtrips and (ii) of the various longitudinal and transverse bulk waves propagating through the Cylinder or reflected at the free circular Surface.
G. W. Rankin - One of the best experts on this subject based on the ideXlab platform.
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The role of turbulence length scale and turbulence intensity on forced convection from a heated horizontal circular Cylinder
Experimental Thermal and Fluid Science, 2007Co-Authors: David S K Ting, G. W. RankinAbstract:Abstract The effects of turbulence integral length scale and turbulence intensity on the convective heat transfer rate from a heated circular Cylinder in crossflow of air were investigated. An aluminium Cylinder of diameter 50.8 cm (2″) and with uniform Surface temperature was placed horizontally in a wind tunnel. The Cylinder was subjected to a homogeneous, isotropic turbulent flow, which was generated using a perforated plate. The Cylinder Surface temperature was monitored and measured with five embedded thermocouples. Tests were conducted at a Reynolds number of 27,700, relative turbulence intensity, Tu from 2.9% to 8.3% and turbulence integral length scale to Cylinder diameter ratio, L / D from 0.50 to 1.47. For L / D = 0.78, heat transfer increased with increasing turbulence intensity, whereas for Tu = 6.9%, heat transfer decreased with increasing turbulence length scale.
Haecheon Choi - One of the best experts on this subject based on the ideXlab platform.
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suboptimal feedback control of vortex shedding at low reynolds numbers
Journal of Fluid Mechanics, 1999Co-Authors: Chulhong Min, Haecheon ChoiAbstract:The objective of this study is to develop a method of controlling vortex shedding behind a bluff body using control theory. A suboptimal feedback control procedure for local sensing and local actuation is developed and applied to the flow behind a circular Cylinder. The location of sensors for feedback is limited to the Cylinder Surface and the control input from actuators is the blowing and suction on the Cylinder Surface. Three different cost functionals to be minimized ( J 1 and J 2 ) or maximized ( J 3 ) are investigated: J 1 is proportional to the pressure drag of the Cylinder, J 2 is the square of the difference between the target pressure (inviscid flow pressure) and real flow pressure on the Cylinder Surface, and J 3 is the square of the pressure gradient on the Cylinder Surface, respectively. Given the cost functionals, the flow variable to be measured by the sensors and the control input from the actuators are determined from the suboptimal feedback control procedure. Several cases for each cost functional have been numerically simulated at Re = 100 and 160 to investigate the performance of the control algorithm. For all actuations, vortex shedding becomes weak or disappears, and the mean drag and drag/lift fluctuations significantly decrease. For a given magnitude of the blowing/suction, reducing J 2 provides the largest drag reduction among the three cost functionals.
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laminar flow past a rotating circular Cylinder
Physics of Fluids, 1999Co-Authors: Sangmo Kang, Haecheon Choi, Sangsan LeeAbstract:The present study numerically investigates two-dimensional laminar flow past a circular Cylinder rotating with a constant angular velocity, for the purpose of controlling vortex shedding and understanding the underlying flow mechanism. Numerical simulations are performed for flows with Re=60, 100, and 160 in the range of 0⩽α⩽2.5, where α is the circumferential speed at the Cylinder Surface normalized by the free-stream velocity. Results show that the rotation of a Cylinder can suppress vortex shedding effectively. Vortex shedding exists at low rotational speeds and completely disappears at α>αL, where αL is the critical rotational speed which shows a logarithmic dependence on Re. The Strouhal number remains nearly constant regardless of α while vortex shedding exists. With increasing α, the mean lift increases linearly and the mean drag decreases, which differ significantly from those predicted by the potential flow theory. On the other hand, the amplitude of lift fluctuation stays nearly constant with in...
