Wake Flow of Single and Multiple Yawed CylindersSource: Journal of Fluids Engineering:;2004:;volume( 126 ):;issue: 005::page 861Author:A. Thakur
,
Graduate Research Assistant
,
X. Liu
,
Graduate Research Assistant
,
J. S. Marshall
,
Professor and Chair
DOI: 10.1115/1.1792276Publisher: The American Society of Mechanical Engineers (ASME)
Abstract: An experimental and computational study is performed of the wake flow behind a single yawed cylinder and a pair of parallel yawed cylinders placed in tandem. The experiments are performed for a yawed cylinder and a pair of yawed cylinders towed in a tank. Laser-induced fluorescence is used for flow visualization and particle-image velocimetry is used for quantitative velocity and vorticity measurement. Computations are performed using a second-order accurate block-structured finite-volume method with periodic boundary conditions along the cylinder axis. Results are applied to assess the applicability of a quasi-two-dimensional approximation, which assumes that the flow field is the same for any slice of the flow over the cylinder cross section. For a single cylinder, it is found that the cylinder wake vortices approach a quasi-two-dimensional state away from the cylinder upstream end for all cases examined (in which the cylinder yaw angle covers the range 0≤ϕ≤60°). Within the upstream region, the vortex orientation is found to be influenced by the tank side-wall boundary condition relative to the cylinder. For the case of two parallel yawed cylinders, vortices shed from the upstream cylinder are found to remain nearly quasi-two-dimensional as they are advected back and reach within about a cylinder diameter from the face of the downstream cylinder. As the vortices advect closer to the cylinder, the vortex cores become highly deformed and wrap around the downstream cylinder face. Three-dimensional perturbations of the upstream vortices are amplified as the vortices impact upon the downstream cylinder, such that during the final stages of vortex impact the quasi-two-dimensional nature of the flow breaks down and the vorticity field for the impacting vortices acquire significant three-dimensional perturbations. Quasi-two-dimensional and fully three-dimensional computational results are compared to assess the accuracy of the quasi-two-dimensional approximation in prediction of drag and lift coefficients of the cylinders.
keyword(s): Flow (Dynamics) , Cylinders , Vortices , Wakes , Yaw AND Wake turbulence ,
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contributor author | A. Thakur | |
contributor author | Graduate Research Assistant | |
contributor author | X. Liu | |
contributor author | Graduate Research Assistant | |
contributor author | J. S. Marshall | |
contributor author | Professor and Chair | |
date accessioned | 2017-05-09T00:13:20Z | |
date available | 2017-05-09T00:13:20Z | |
date copyright | September, 2004 | |
date issued | 2004 | |
identifier issn | 0098-2202 | |
identifier other | JFEGA4-27201#861_1.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl/handle/yetl/130197 | |
description abstract | An experimental and computational study is performed of the wake flow behind a single yawed cylinder and a pair of parallel yawed cylinders placed in tandem. The experiments are performed for a yawed cylinder and a pair of yawed cylinders towed in a tank. Laser-induced fluorescence is used for flow visualization and particle-image velocimetry is used for quantitative velocity and vorticity measurement. Computations are performed using a second-order accurate block-structured finite-volume method with periodic boundary conditions along the cylinder axis. Results are applied to assess the applicability of a quasi-two-dimensional approximation, which assumes that the flow field is the same for any slice of the flow over the cylinder cross section. For a single cylinder, it is found that the cylinder wake vortices approach a quasi-two-dimensional state away from the cylinder upstream end for all cases examined (in which the cylinder yaw angle covers the range 0≤ϕ≤60°). Within the upstream region, the vortex orientation is found to be influenced by the tank side-wall boundary condition relative to the cylinder. For the case of two parallel yawed cylinders, vortices shed from the upstream cylinder are found to remain nearly quasi-two-dimensional as they are advected back and reach within about a cylinder diameter from the face of the downstream cylinder. As the vortices advect closer to the cylinder, the vortex cores become highly deformed and wrap around the downstream cylinder face. Three-dimensional perturbations of the upstream vortices are amplified as the vortices impact upon the downstream cylinder, such that during the final stages of vortex impact the quasi-two-dimensional nature of the flow breaks down and the vorticity field for the impacting vortices acquire significant three-dimensional perturbations. Quasi-two-dimensional and fully three-dimensional computational results are compared to assess the accuracy of the quasi-two-dimensional approximation in prediction of drag and lift coefficients of the cylinders. | |
publisher | The American Society of Mechanical Engineers (ASME) | |
title | Wake Flow of Single and Multiple Yawed Cylinders | |
type | Journal Paper | |
journal volume | 126 | |
journal issue | 5 | |
journal title | Journal of Fluids Engineering | |
identifier doi | 10.1115/1.1792276 | |
journal fristpage | 861 | |
journal lastpage | 870 | |
identifier eissn | 1528-901X | |
keywords | Flow (Dynamics) | |
keywords | Cylinders | |
keywords | Vortices | |
keywords | Wakes | |
keywords | Yaw AND Wake turbulence | |
tree | Journal of Fluids Engineering:;2004:;volume( 126 ):;issue: 005 | |
contenttype | Fulltext |