界面活性剤水溶液の抵抗減少流れにおけるストリーク構造(<小特集>乱流せん断流の制御)

概要

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The characteristics of low-speed streaks in turbulent channel flow of a drag-reducing surfactant solution are studied by employing the hydrogen-bubble flow visualization method. The mean velocity profiles and the distributions of streamwise turbulence intensity are also obtained. It is shown that at large values of the drag reduction ratio DR, the profile of the streamwise turbulence intensity has a plateau region around its peak. In the flow of drag-reducing surfactant solution, the mean spanwise streak spacing reaches a minimum at some distance from the wall. In the flow of drag-reducing high density (1000 ppm) surfactant solution, low-speed streaks appear intermittently at a Reynolds number smaller than those for the 'hump' of the f-Re curve (f: friction factor). The mean spanwise streak spacing very near the wall increases as DR increases. It is speculated that the nondimensional wall-normal distance y^+ of the center of streamwise vortices is larger for the flow of large DR compared with that for Newtonian fluid flow.
一般社団法人日本機械学会の論文
1997-01-25