AM06-03-009 チャネル乱流内の流体線伸長における非等方性(乱流渦構造(2),一般講演)

概要

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Anisotropy of stretching of a passive material line and a infinitesimal element in a turbulent channel flow is studied at Re_Τ=180 using direct numerical simulation (DNS). A series of DNS has been performed with various initial position and alignment of the line. We examined evolution of the line, which is initially aligned with either of the three coordinate axes (streamwise, wall-normal or spanwise direction). It is revealed that, at this Reynolds number, the deformations of a spanwise material line (at y^+=15) and a wall-normal one are more rapid than a streamwise line. The fractal (correlation) dimension of the lines is found to increase with time, and its temporal variation also reveals the initial-condition dependence of the line deformation. It is shown qualitatively by visualization of a crosssectional flow that a streamwise vortex and a burst phenomenon cause the intensive stretching and the anisotropy of the line deformation.
日本流体力学会の論文
2006-09-05