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429 results on '"Lu, Xi-Yun"'

102. Turbulent Boundary Layer Control via a Streamwise Travelling Wave Induced by an External Force

Author

Gao Peng, LU Xi-Yun, Qin Tong, and Liu Nan-sheng

Subjects
Physics::Fluid Dynamics, Physics, Boundary layer, Flow separation, Classical mechanics, Parasitic drag, Drag, Turbulence, Direct numerical simulation, Fluid dynamics, General Physics and Astronomy, Laminar sublayer, Mechanics
Abstract

Turbulent boundary layer control via a streamwise travelling wave is investigated based on direct numerical simulation of an incompressible turbulent channel Sow. The streamwise travelling wave is induced on one side wall of the channel by a spanwise external force, e.g., Lorenz force, which is confined in the viscous sublayer. As the control strategy used in this study has never been examined, we pay our attention to its efficiency of drag control. It is revealed that the propagating direction of the travelling wave, i.e., the downstream or upstream propagating direction with respect to the streamwise Bow, has an important role on the drag control, leading to a significant drag reduction or enhancement for the parameters considered. The coherent structures of turbulent boundary layer are altered and the underlying mechanisms are analysed. The results obtained provide physical insight into the understanding of turbulent boundary layer control.

Published
2008

107. Curvature Effect on Compressible Turbulent Flow over a Wavy Wall

Author

LU Xi-Yun and Sun Xiao-Bo

Subjects
Physics, Chézy formula, Turbulence, Baroclinity, General Physics and Astronomy, Mechanics, Enstrophy, Curvature, Nonlinear Sciences::Chaotic Dynamics, Physics::Fluid Dynamics, Classical mechanics, Physics::Space Physics, Turbulence kinetic energy, Compressibility, Large eddy simulation
Abstract

A fully developed compressible turbulent flow in a channel with a lower wavy wall and a upper plane wall is studied using large eddy simulation. We mainly attempt to deal with the curvature effect on compressible turbulent flow over the wavy wall. Some typical quantities including the mean turbulence statistics, dilatation and baroclinic terms in the enstrophy equation, turbulent kinetic energy budgets and the near-wall turbulent structures are analysed. The results obtained in this study provide physical insight into the understanding of the effects of curvature and compressibility on wall-bounded compressible turbulent flow.

Published
2007

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