OSCILLATORY MOMENTUM TRANSPORT MECHANISMS IN TRANSITIONAL COMPLEX-GEOMETRY FLOWS

This work reports direct numerical simulations of transitional flows i n communicating channels. Above a critical Reynolds number, the flow b ecomes fluctuating and self-sustained with vortical motions temporally synchronized with channel traveling waves. The energy transfer mechan ism between the mean and the fluctuating flow is investigated along wi th the distributions of oscillatory shear stress and transitional visc osity. The kinetic energy equation for the fluctuating velocity is sol ved from DNS data to evaluate the contributions of the production term , viscous dissipation, work of dynamic pressure and work of viscous sh ear stresses.