d 形粗面境界層の乱流構造に関する研究 : レイノルズ数の影響

概要

論文の詳細を見る
Low Reynolds number effect on the turbulent structure of a d-type rough wall boundary layer was investigated experimentally. The measurements were made in the momentum thickness Reynolds number range of R_θ=700-5140,which includes a transitionally and a fully rough regime, and turbulent intensity and Reynolds shear stress distributions and a few turbulent structural parameter were obtained with hot-wire measurement. The scaling laws for both the inner and outer layer structures were examined with the local wall shear stress determined from a direct measurement. Turbulent intensity profiles normalized with the inner-layer scales are hardly similar in the whole Reynolds number range. The constant stress layer in the near-wall region does exist even in the transitionaly rough regime. However, those constant stress values depend on the Reynolds number. When the distributions were normalized with the outer-layer scales, only the u_<rms> component takes similar profile down to the lowest Reynolds number, R_θ=700. The turbulent intensity and Reynolds shear stress of the present d-type rough wall flow are larger than that of the smooth wall flow even at R_θ=700-790 where the skin friction coefficient of the present rough wall flow is almost the same as that of the smooth wall flow.
山口大学の論文