Interacting Particle-Liquid Systems

We present two Euler-Lagrangian simulation methods for particles immersed in fluids described by the Navier-Stokes equation. These implement the coupling between particle and fluid phase by (i) direct integration of the stress tensor on the particle surface discretized according to the grid topology and (ii) by a tracer particle method, which employs the volume force term in the Navier-Stokes equation to emulate “rigid” body motion. Both methods have been parallelized and applied to bulk sedimentation of about 65 000 particles (in one simulation 106 particles have been simulated). We also report results for the rheology of shear-thinning suspensions, modelled by hydrodynamically interacting particles in shear flows. Aggregation occurs due to attractive, short range forces between the particles. We also address a deficiency of the MPI communication library on the CRAY T3E which had to be resolved to improve the performance of our algorithm.