Oscillatory Momentum Transport Mechanisms in Transitional Complex Geometry Flows

Abstract

This work reports direct numerical simulations of transitional flows in communicating channels. Above a critical Reynolds number, the flow becomes fluctuating and self-sustained with vortical motions temporally synchronized with channel traveling waves. The energy transfer mechanism between the mean and the fluctuating flow is investigated along with the distributions of oscillatory shear stress and transitional viscosity. The kinetic energy equation for the fluctuating velocity is solved from DNS data to evaluate the contributions of the production term, viscous dissipation, work of dynamic pressure and work of viscous shear stresses.