完全相似条件を満足する粗面乱流境界層の実現とその平均流特性(流体工学,流体機械)

概要

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Mean flow quantities have been investigated for the equilibrium boundary layer developing over the rough surface with roughness height proportional to streamwise distance. The wall shear stress was measured by direct measurement with a floating element device of zero displacement mechanism. Local skin friction coefficient is independent of two parameters both streamwise coordinate and Reynolds number based on momentum thickness and has a value of 0.0826. The boundary layer thickness is proportional to the streamwise distance. Then, the relative roughness height keeps a constant value. The log-law profile has same slope of that for the smooth wall turbulent boundary layer in the logarithmic linear part. The value of the roughness function increases in the streamwise direction. The wake parameter approaches to the constant value of about 0.7. Also, the value is consistent with the result deduced from the analytical method used both the momentum integral equation and Coles's wake law. Then, the wake parameter decreases with increasing the friction parameter.
社団法人日本機械学会の論文
2006-05-25