k-εモデルによる二次元粗滑面非対称チャンネル弛緩流れの有限要素解析

概要

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A high-Reynolds-number k-ε model is used to predict the relaxation process which develops in the channel whose upstream half wall is made rough. Experimental evidence shows that after the step change in wall roughness, the mixing length increases considerable over the value expected in the ordinary boundary layer. It is also shown that the convection term in the turbulence kinetic energy equation is not negligible and the existence of the wall equilibrium layer is not expected. Therefore, two new refinements are applied to the boundary condition adjacent to the wall. One is that the Karman constant in the logarithmic law of the wall is assumed to vary with streamwise distance. The other is that all the terms in the turbulence energy equation are considered. It is found that the prediction of the variation in the mean velocity is improved and the abrupt decrease in the turbulence kinetic energy, which is found in the usual model, disapears.
社団法人日本機械学会の論文
1989-01-25