斜め後方ステップ流れに関する実験的研究 : 第2報,再付着後の変動速度場(流体工学,流体機械)

概要

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The reattaching flow behind a swept backward-facing step, at a Reynolds number Re_m=8000 for the swept angle of 30 degrees, is investigated experimentally. Measurements for the turbulent flow field are made by using the rotated hot-wire method. In the early stage of the recovery region, all components of fluctuating velocities and Reynolds shear stresses have large values in the middle region of the boundary layer compared to those in two-dimensional boundary-layer. This may be attributed mainly to the large values of turbulent-energy and Reynolds-stress production terms as well as the advection of the highly turbulent fluid from the upstream. The eddy-viscosity ratio exhibits anisotropy of the eddy viscosity in the near region of the reattachment. To examine anisotropy of the eddy viscosity a comparison is made of the directions of the shear-stress vector and the strain vector. The difference of these angles becomes smaller as goes to the downstream, and the eddy viscosity could be presumed isotropic in the region of x/H>12.5. The structure parameter varies from a larger value just behind the reattachment point than in two-dimensional flows to the value of two-dimensional flow in the far downstream.
社団法人日本機械学会の論文
2005-03-25