Production and transport of turbulent helicity in turbulent channel flow with wall-normal system rotation

Abstract

Turbulent helicity is known to be generated in the boundary layer when the system is rotated perpendicular to the wall. In order to consider the production and transport mechanism, we used LES of wall-normal rotating turbulent channel flow to investigate the contribution of each term in the budgets of the turbulent helicity and its three parts h_xx, h_yy and h_zz. We found that the pressure-diffusion term had the most contribution to the generation of the turbulent helicity throughout the whole region when the rotation parameter was as small as 0.01-0.02. However, if we decompose the turbulent helicity into three terms, the contribution of the production term is the largest in the budgets of h_xx and h_zz, which are superior to h_yy.