Relaminarization of turbulent channel flow using traveling wave-like wall deformation

Effect of traveling wave-like wall deformation (i.e. peristalsis) in a fully developed turbulent channel flow is investigated by means of direct numerical simulation. We not only demonstrate that the friction drag is reduced by wave-like wall deformation traveling toward the downstream direction, but also show that the turbulence is completely suppressed (viz. the flow is relaminarized) under some sets of parameters. It is also found that at higher amplitude of actuation the relaminarized flow is unstable and exhibits a periodic cycle between high and low drag. The drag reduction is caused by suppression of random Reynolds shear stress component due to stabilization. The quadrant analysis reveals that traveling wave-like wall deformation makes strongly negative random Reynolds shear stress in the converging region.