A fast multipole boundary element method implemented for wet single particle and wall interactions

The progress is described in developing a parallel computer code to study the dynamics of wet granular systems based on the Fast Multi-pole Boundary Element Method (FMBEM). Here, three examples are considered that have closed-form or numerical solutions and thus able to act as benchmarks. They involved capillary interactions, the formation of a solid-solid contact when a particle approaches a solid wall while immersed in a Newtonian fluid, and the isoviscous hydrodynamic and elastohyrodynamic sliding of a particle. While computationally more expensive than DEM, there are a number of advantages such as extending interactions from the pendular to more saturated states, the ease with which non-spherical particles can be modelled and the ability to model
wet granular systems that may exhibit transitions from frictional to lubricated flow. Consequently, FMBEM is able to modelwet agglomeratesmore realistically than DEMand this is important for improving the performance of twin screw granulation, which is the intended application of the current work.