An efficient and robust GPGPU-parallelized contact algorithm for the combined finite-discrete element method

In this study, an efficient and robust GPGPU (general purpose graphic processing unit)-parallelized algorithm is proposed for contact force calculation for the three-dimensional combined finite-discrete element method (3D FDEM). The contact force model is energy-conserving and avoids the issues that the mesh-dependence of contact force in the original contact algorithm proposed by Munjiza. The contact force calculation is based on the determination of the geometrical features of the overlapped region between two particles, which can be easily obtained by performing the face-particle intersection calculations consecutively. The contact damping and contact friction are also implemented. Based on Compute Unified Device Architecture (CUDA), the proposed contact algorithm can be parallelized with much less thread unbalance and register usage than the existing energy-conserving contact algorithms due to the simplified computational process. Several numerical tests are performed to validate the efficiency and effectiveness of the proposed contact algorithm. The contact friction model is validated against theoretical solutions with a block sliding test, and the results show that the proposed contact algorithm outperforms the original contact algorithm in both normal and friction force evaluation. For both quasi-static and dynamic scenarios, the simulated results are in good agreement with those generated by the original contact algorithm, as well as the experimental measurements. The computational efficiency tests show that the computation time is linearly proportional to the number of potential contact pairs, and the speedup ratio of the parallelized version of proposed contact algorithm relative to the serial version of original contact algorithm can reach up to 565.1 (Nvidia Quadro GP100), which indicates the proposed contact algorithm is capable to be employed in the simulation of large-scale problems. Besides, the proposed contact algorithm can be applied to the cases where the polyhedrons with more than four vertexes are employed.(c) 2022 Elsevier B.V. All rights reserved.