粗面クエット流において発生する様々な準秩序構造

抄録

Most wall-bounded shear flows undergo a subcritical transition scenario. The lowest limit of the transitional regime features intermittent coherent structures that are, for instance, turbulent-laminar patterns in plane channel flows. The transitional phenomena on smooth walls have been considered well; however, walls in industrial situations have hydro-dynamically roughened surface, since a perfectly smooth wall is ideal and uneconomic for production. The aim of this study is to elucidate the influence of roughness on the turbulent-laminar patterns and to evaluate the robustness of the turbulent-laminar patterns on the roughness wall. We study plane Couette flows with one/two rough wall(s) by means of direct numerical simulation and found several flow structures in roughness induced regime.