B-232 チャンネル乱流中の Coherent 微細渦に作用するひずみ場

概要

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To clarify a relation between strain rate field and coherent fine scale eddies in wall turbulence, we conducted direct numerical simulation for a turbulent channel flow. Eigen values of the strain rate tensor at the center of coherent fine scale eddies are of the order of η/μ_k, in the near wall, the most expected maximum and minimum eigen value slightly increase and decrease, respectively. However, away from the wall, the strain rates acting on the coherent fine scale eddies coincide with those in homogeneous turbulence and turbulent mixing layer. The eigen vectors of the minimum eigen value and maximum eigen value tend to be perpendicular to the axis, and the most expected angle between rotating axis and eigen vector of intermediate eigen value is about 14∿15 degrees near the wall. On the plane perpendicular to the axis, contours of the mean maximum and minimum eigen values have a maxima on major axis and two minima on minor axis near the wall. Far from the wall, they become to show two symmetric maxima and minima.
日本流体力学会の論文
2003-07-28