Simulation of the interaction between nonspherical particles within the CFD-DEM framework via multisphere approximation and rolling resistance method

摘要

The particle shape is an important factor playing critical role in evaluation of the interactions between particles in high-concentration particle-fluid flows. In this paper, the well-known multisphere (MS) approximation approach and the novel rolling resistance approach are utilized to examine their performance in order to simplify the generalized shaped particle's interactions within the framework of discrete element method (DEM) and computational fluid dynamics (CFD). The performance of two approaches are compared with the perfect particle's shape geometry, for the limited cases of cubic-shaped and disk-shaped particle flows in a horizontal well drilling process as a reference scenario. Deviation of the MS approximation shape from the perfect particle geometry is evaluated by comparison of macroscopic properties of nonspherical particle. It is determined that the data on macroscopic parameters yielded by the MS model tend to converge to those of the smooth particle with the increasing number of the subspheres. Moreover, the effectiveness of rolling resistance method is investigated by comparison of macroscopic properties of nonspherical particles with approximated MS approach and approximated spherical particles subjected to the rolling friction. The results show that the updated rolling resistance model can reduce the inaccuracy in the prediction of the particles deposit originated from the spherical shape idealization fairly and can be considered where the cost of computations is a restrictive issue.