Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 29, 2018 - November 30, 2018
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, Reτ ～ 105 − 106.
