ON THE APPLICATION OF A NOVEL ALGORITHM TO HYDRODYNAMIC DIFFUSION ANDVELOCITY FLUCTUATIONS IN SEDIMENTING SYSTEMS

We present a numerical method to deal efficiently with large numbers o f particles in incompressible fluids. The interactions between particl es and fluid are taken into account by a physically motivated ansatz b ased on locally defined drag forces. We demonstrate the validity of ou r approach by performing numerical simulations of sedimenting non-Brow nian spheres in two spatial dimensions and compare our results with ex periments. Our method reproduces qualitatively important aspects of th e experimental findings, in particular the strong anisotropy of the hy drodynamic bulk self-diffusivities.