Open-Source Direct Numerical Simulation Framework for Fluid-Particle Systems

Direct numerical simulations are of great importance for understanding fluid-particles system happening in both nature and industrial process. However, they are computationally very expensive due to the requirement of resolving flows around large number of particles. To tackle this challenge, we developed a high-performance simulation framework by coupling the discrete element method (DEM) and lattice Boltzmann method (LBM). To utilize the latest supercomputers, we choose the high-level mesoscale modeling system and its backend, multiplatform lattice Boltzmann code for the LBM part. Based on the domain specific language approach, the LBM simulations can be deployed in the MPI+X fashion. For the DEM part, we employ the LAMMPS/LIGGGHTS family, which is highly parallelized. To couple the two heterogeneous solvers, an interface is developed on the basis of the multiscale universal interface library (MUI). Minimal modifications are introduced to facilitate data exchange between the LBM and the DEM solvers which are needed by the partially saturated method. Numerical simulations were conducted to verify the framework by using the cases of particle sedimentation and the 3D channel flow around a fixed sphere. The parallel efficiency was evaluated for a large system of particles migrating in a pipe. Finally, the particle migration in a three-dimensional L-pipe was simulated to further demonstrate the capability.