進行波状壁面変形によるチャネル乱流抵抗低減のレイノルズ数効果

抄録

We perform direct numerical simulation of turbulent channel flow with traveling wave-like wall deformation at three different friction Reynolds numbers, Reτ = 90, 180, and 360. It is found that the set of control parameters in the maximum drag reduction case is same in wall units: there is little Reynolds number dependency in the mean velocity profiles under this set of control parameters. Based on this scaling, we propose a semi-empirical formula for the mean velocity profile to predict the drag reduction rate at higher Reynolds numbers. Using the proposed formula, it is revealed that about 40% drag reduction effect can be attained even at practically high Reynolds numbers, Re_τ ～ 10⁵ − 10⁶.