Large Eddy Simulation of turbulent Couette-Poiseuille flows in a square duct

Abstract

The large eddy simulation (LES) method is applied to simulate turbulent Couette-Poiseuille flows in a square duct. The moving wall would effectively reduce the mean shear near the wall, and hence the turbulent structures and the secondary flow patterns within the duct are modified. The formation of the secondary motion is further investigated by analyzing the stream-wise mean vorticity transport equation. The fully developed turbulent Couette-Poiseuille flow in a square duct is simulated using LES. The focus is on the secondary flow near the moving wall. Results of present simulation show one dominate vortex and a relatively small vortex near the moving wall. They block the high-momentum fluid near the center of the duct into the corner regions, and have different effects on both the wall shear stress distribution and turbulence statistics compared to that near the stationary wall. The generation of the secondary flow is further investigated by studying the stream-wise vorticity transport equation. The major generation mechanism of the dominate vortex is the normal Reynolds stress anisotropy, and the viscous diffusion and the Reynolds shear stress anisotropy act as transport mechanisms for the mean vorticity.