Mechanism of controlling turbulent channel flow with the effect of spanwise Lorentz force distribution  

作　　者：韩洋 张辉 范宝春 李健 江代文 赵子杰 

机构地区：[1]Science and Technology on Transient Physics Laboratory,Nanjing University of Science and Technology,Nanjing 210094,China

出　　处：《Chinese Physics B》2017年第8期250-258,共9页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11672135 and 11202102);the Fundamental Research Funds for the Central Universities,China(Grant No.30916011347);a Foundation for the Author of National Excellent Doctoral Dissertation,China(Grant No.201461)

摘　　要：A direct numerical simulation（DNS） is performed to investigate the control effect and mechanism of turbulent channel flow with the distribution of spanwise Lorentz force. A sinusoidal distribution of constant spanwise Lorentz force is selected, of which the control effects, such as flow characters, mean Reynolds stress, and drag reductions, at different parameters of amplitude A and wave number k_x are discussed. The results indicate that the control effects vary with the parameter A and k_x. With the increase of A, the drag reduction rate D_r first increases and then decreases rapidly at low k_x,and slowly at high k_x. The low drag reduction（or even drag increase） is due to a weak suppression or even the enhancements of the random velocity fluctuation and mean Reynolds stress. The efficient drag reduction is due to the quasi-streamwise vortex structure induced by Lorentz force, which contributes to suppressing the random velocity fluctuation and mean Reynolds stress, and the negative vorticity improves the distribution of streamwise velocity. Therefore, the optimal control effect with a drag reduction of up to 58% can be obtained.A direct numerical simulation（DNS） is performed to investigate the control effect and mechanism of turbulent channel flow with the distribution of spanwise Lorentz force. A sinusoidal distribution of constant spanwise Lorentz force is selected, of which the control effects, such as flow characters, mean Reynolds stress, and drag reductions, at different parameters of amplitude A and wave number k_x are discussed. The results indicate that the control effects vary with the parameter A and k_x. With the increase of A, the drag reduction rate D_r first increases and then decreases rapidly at low k_x,and slowly at high k_x. The low drag reduction（or even drag increase） is due to a weak suppression or even the enhancements of the random velocity fluctuation and mean Reynolds stress. The efficient drag reduction is due to the quasi-streamwise vortex structure induced by Lorentz force, which contributes to suppressing the random velocity fluctuation and mean Reynolds stress, and the negative vorticity improves the distribution of streamwise velocity. Therefore, the optimal control effect with a drag reduction of up to 58% can be obtained.

关 键 词：flow control turbulent channel flow Lorentz force direct numerical simulation 

分 类 号：O357.5[理学—流体力学]