スパン方向壁面運動による壁近傍の縦渦および低速ストリークの崩壊過程(流体工学,流体機械)

概要

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Two dimensional Poiseuille turbulent flow is subjected to spanwise motion of the lower wall of a channel flow. Direct Numerical Simulation (DNS) is used to investigate the response of coherent structures which exist in the near-wall region to the wall motion for the initial period (t^+_δ≤0.5). There is asymmetry in the response of streamwise vortices. Upstream ends of positive vortices leave away from the wall and lose the ability to wind up the spanwise vortex line, while those of negative vortices are bent towards the positive spanwise direction but remain close to the wall. This difference makes the positive vortices decay earlier than the negative vortices. Low-speed streak is torn into pieces at the overlapped region between the positive and the negative vortices. The bottom of the low-speed streak is also pared off due to the strong enstrophy.
社団法人日本機械学会の論文
2005-10-25