A unified level set method for simulating mixed granular flows involving multiple non-spherical DEM models in complex structures

Abstract

Since the mixed granular flows containing multiple non-spherical DEM models in complex structures are still challenging for DEM applications, a unified method for creating level set functions of arbitrarily shaped particles constructed by different non-spherical DEM models was developed, and a particle–structure contact algorithm was proposed. At the initial moment, particles of arbitrary shapes constructed by spheres, superquadric equations, spherical harmonic functions, and polyhedral models were discretized using spatial level set functions, and complex structures were discretized into a series of triangular elements. Hence, the contact problem between arbitrarily shaped particles and complex structures was solved using the proposed contact algorithm between level set functions and triangular elements. Meanwhile, particle–particle contact points in mixed granular systems containing multiple non-spherical DEM models were calculated using the level set method . To examine the conservation, accuracy, and robustness of the proposed model, four sets of tests were performed and compared with the theoretical and experimental results, including a plane impacted by a single particle, the elastic collision between two particles, the accumulation of multiple particles, and the mixed granular flow in complex structures. The corresponding numerical results are in good agreement with the theoretical and experimental results, verifying that the present DEM model can accurately predict the motion characteristics of different non-spherical DEM models and can be widely applied to mixed granular flows involving multiple DEM models in complex structures.