Turbulent channel flow controlled by traveling-wave-like body force mimicking oscillating thin films

Abstract

To improve energy efficiency, flow control techniques for skin-friction drag and heat transfer with regard to wall turbulence are essential. This study performs direct numerical simulation of turbulent channel flows. The traveling-wave-like body force is employed as the flow control technique to break the similarity between momentum and heat transfer. The traveling wave control mimics the self-excited thin film in the corresponding experimental study. When the wave traveled slowly along the downstream direction, the skin-friction drag, heat transfer, and analogy factor were found to increase. Moreover, these parameters increased with an increase in the reference height of the traveling wave ( hw). Flow visualization shows turbulence enhancement owing to the increase in hw. Three-component decomposition elucidates the difference between the control effect on the Reynolds shear stress and the turbulent heat flux.