Mechanisms of drag reduction by semidilute inertial particles in turbulent channel flow

Abstract

We show that significant drag reduction can be achieved in a turbulent channel flow using appropriately scaled mono-disperse particles. We show that drag-reducing particles form very long ropes along the channel wall. These particle ropes interfere with the near-wall turbulence regeneration mechanisms, which causes partial re-laminarization of the flow and significant reduction of skin-friction drag.