Wall Turbulent Flow with Mean Skewed Velocity : (1st Report, Mean Velocity and Statistic Properties of Turbulence)

Abstract

The skewed wall turbulent flow, driven by sudden span wise wall motion superimposed on plane Poiseulle flow, has been simulated by Direct Numerical Simulation (DNS). The time evolution of the mean velocities and the Reynolds stresses have been studied. Just after the spanwise wall motion starts the flow skewness is confined to the narrow wall region (y⁺<30) and the flow soon becomes another collateral flow again. During the evolution stage, turbulent kinetic energy first decreases and then increases. The time when q^^-2 takes its minimum depends on the Reynolds number of the flow. The difference between shear driven and pressure driven skewed flow is also shown. The production and pressure strain terms in the Reynolds stress transport equation are shown to play an important role in leading to non parallel vectors of velocity gradient and Reynolds shear stresses.