Efficient numerical methods for the simulation of particulate and liquid-solid flows

Abstract

In this work a set of efficient numerical methods for the simulation of particulate flows and virtual prototyping applications are proposed. These methods are implemented as modular components in the FEATFLOW software package which is used as the fluid flow solver. In direct particulate flow simulations the calculation of the hydrodynamic forces acting on the particles is of central importance. For this task acceleration techniques are proposed based on hierarchical spatial partitioning. For arbitrary shaped particles the usage of distance maps to rapidly process the needed geometric information is employed and analyzed. In case of collisions between the particles it is shown how these same structures can be used to efficiently handle the collision broad phase and narrow phase. The computation of collision forces in the proposed particulate flow solving scheme can be handled by several collision models. The used models are based on a constrained-based formulation which leads to a linear complementarity problem (LCP). Another approach is added into the particulate flow solver that is based on the discrete element method (DEM). This approach is suited very well to an Implementation on graphic processing units (GPU) as the particles can be handled independently and thus excellent use of the massive parallel computing capabilities of the GPU can be made. In order to extend the DEM to handle non-spherical particles or rigid bodies, an inner sphere representation of such shapes is used. Furthermore, a mesh adaptation technique to increase the numerical efficiency of the CFD-simulations is shown which is based on Laplacian smoothing with special weights. The proposed techniques are validated in various benchmark configurations or comparisons to experimental data.