Accumulated densities of sedimenting particles in turbulent flows

We study the effect of turbulence on a sedimenting layer of particles by means of direct numerical simulations. A Lagrangian model in which particles are considered as tracers with a downward settling velocity is integrated together with an isotropic homogeneous turbulent flow. Particles initially distributed on the upper plane of the computational box are released and collected at the bottom. We investigate the distribution of particles at the accumulation plane and the inhomogeneities developing during non-asymptotic finite settling times. We relate the resulting coarse-grained particle density to the history of the stretching rate along the particle trajectory and its projection onto the accumulation plane, and analyse the degree of clustering and the deviation from homogeneity.