Direct numerical simulation of streamwise traveling wave induced turbulent pipe flow relaminarization

Abstract

In pipe flows at high Reynolds numbers, more than 90% of the pumping power is dissipated by near-wall turbulence, making relaminarization a promising strategy for saving energy. Streamwise traveling waves of wall blowing and suction, previously proven able to relaminarize turbulent pipe flow at Ret=utR/ν=110, are here demonstrated to achieve relaminarization up to Ret=540. Here, ut is the friction velocity, R the pipe radius, and ν the kinematic viscosity. Independent of the Reynolds number, the relaminarization requires 130R/ut for the drag reduction rate to converge. The resulting flow structure combines viscous-scaled half-vortices superimposed on the radius-scaled laminar profile. These results establish scaling relations that extend traveling wave–induced relaminarization to higher Reynolds numbers, offering a predictive framework for energy-efficient flow control.