ギャップをもつ粗さ要素を通過する乱流境界層における縦渦 : 流れ方向渦度輸送方程式における生成項の評価

概要

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In a turbulent boundary layer distorted by spanwise gaps between roughness elements, the skew-induced and stress-induced production terms in the vorticity transport equation have been examined experimentally. The skew-induced production maintains both vortices of negative and positive vorticity generated behind the spanwise gaps, and the reorientation mechanism is recognized in the contribution mostly given by a component -∂W/∂x・∂U/∂y due to the mean streamlines curvature depending on size of spanwise gap. The Reynolds shear stress component -<uw>^^-, which also contributes to maintenance of the streamwise vortex through the stress induced production term, is correlated with the velocity gradients, ∂U/∂z and ∂W/∂y, rather than the mean streamline curvature ∂W/∂x. Meaning of the classification for gap size, i.e. S-gap, M-gap, and L-gap, appears in features of cross-stream distributions of the stress induced production due to non-isotropy of Reynolds normal stresses.
1999-07-25