遷移粗さおよび完全粗面領域におけるd形粗面境界層の平均量特性

概要

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Mean flow properties of a d-type rough wall boundary layer in a transitionally and a fully rough regime have been examined experimentally. The mean velocity, the turbulent intensities of three components and the Reynolds shear stress were measured over the momentum thickness Reynolds number R_θ=700〜5140. Even in a transitionally rough regime, the logarithmic layer is confirmed and the value of the karman constant is the same value as that of the smooth wall flow. However, the velocity defect law has been found to be dependent on R_θ. The variation of the wake parameter Π with R_θ is significantly different from that of the smooth wall flow. The u_<rms>/u_τ profiles normalized with the inner variables indicate reasonable similarity for R_θ≧3200 in the inner layer, while these profiles normalized with the outer variables are similar in the outer region. The v_<rms>/u_τ and the w_<rms>/u_τ profiles do not exhibit similarity in their dependence on R_θ. The Reynolds shear stress -<uv>^^-/u^2_τ profiles show the constant stress layer over the complete Reynolds number range, but these constant values depend on the Reynolds number.
1989-03-25