Systematic development of an equivalent particle method for efficient simulation of dense granular flows

Abstract

Development of a highly efficient model is very important to expand the applicability of discrete element method (DEM) to large-scale granular flows that often include a tremendous number of granular particles. An equivalent particle method is rigorously developed for such a purpose in this study. The kinetic theory for granular flows is taken advantage to understand the relationship between the original particle system and the equivalent particle system, with a focus on conservation of mass and momentum. With the newly established equivalent particle method, the averaged particle velocity, density and volume concentration remain the same as in the original system. Scaling factors for other physical quantities, particularly those describing particle contact processes, are introduced to satisfy the geometric, kinematic and dynamic similarities. Verification of the equivalent particle model are performed by applying it to the computation of granular collapses on both horizontal and inclined bottoms. The computational results on deformation of granular profiles show that existing coarse grain or representative particle models, which were developed for the similar purpose as the present equivalent particle model, underestimate the granular material’s mobility. The numerical results from the present model agree much better with experimental data, indicating a major advancement in this kind of model development. The efficiency is drastically improved by tremendously reducing the number of computed particles, as compared to the standard DEM model.