Sweep-stick mechanism of particle clustering in turbulent flows

Abstract: 

This work focuses on the sweep-stick mechanism of particle clustering in turbulent flows whereby heavy particles cluster in a way which mimics the clustering of zero acceleration points. We present this phenomenology in 2D and 3D homogeneous, isotropic turbulence and turbulent channel flow. Crucial to the mechanism in each case is the nature of sweeping in the flow. We quantify the Stokes number dependency of the probability of the heavy particles to be at zero acceleration points and show that in the inertial range of Stokes numbers the sweep-stick mechanism is dominant over the conventionally proposed mechanism of heavy particles being centrifuged from high vorticity regions to high strain regions.