Reynolds stress in the turbulent channel flow controlled byspanwise travelling wave Lorentz forc

Abstract:

The flow control and drag reduction in a turbulent channel flow by using a spanwise travelling wave Lorentz force are investigated numerically via the direct numerical simulation (DNS). The evolution of the streaks and the vortex structures adjoining the wall in the turbulent channel flow controlled by Lorentz force are described. Moreover, normal fluctuation velocity, streamwise fluctuation velocity distribution, the average Reynolds stress distribution and the spectra analysis of Reynolds stress are also discussed simultaneously. The results show that, under the action of the distributed Lorentz force with proper control parameters, only well-organized strip-shaped streamwise vortexes are observed in the near-wall region of the turbulent channel flow, and the others vortexes are almost disappeared, which is the same as the streaks in the near-wall region. Besides the Reynolds stress in the controlled channel flow was inhibited sharply by the spanwise travelling wave Lorentz force which leads to the reduction of skin-friction drag. The mechanism of turbulence drag reduction controlled by using a spanwise travelling wave Lorentz force is further clarified.