Multi-sphere rigid-body particles in a parallelized LEBC with LIGGGHTS

A method for the Message Passing Interface (MPI) parallelization of the Lees-Edwards boundary condition (LEBC) within the LIGGGHTS framework for multi-sphere rigid particles was created, allowing for the simulation of very detailed complex shapes. Double-send and double-receive communication was added to LIGGGHTS to allow for shared information across disjointed processor domains along the shearing boundary of the LEBC. The verification of this method is performed via 3D shearing simulations of single spheres and sphere clumps and rods with aspect ratios 2, 4, and 6. The predicted shear stress employing the new parallelized LEBC method matches stress values from granular kinetic theory and previously published simulation results. No LEBC simulations for DEM or multi-sphere rigid particles are known to be parallelized, allowing for computationally difficult LEBC multi-sphere simulations to be performed for the first time. Program title: Multi-sphere Parallelized LEBC in LIGGGHTS CPC Library link to program files: https://doi.org/10.17632/v3t758727j.1 Developer's repository link: https://github.com/elizabeth-suehr/LIGGGHTS-LEBC-CFDRC (the LIGGGHTS code) Licensing provisions: GNU General Public License 2 Programming language: C ++ Supplementary material: https://github.com/elizabeth-suehr/dem-scripts (code for work in the paper) Nature of problem: The parallelized Lees-Edward boundary condition is not implemented for any DEM codebases. This would allow for complex particle shapes which are computationally expensive to be simulated in the LEBC, allowing for stress tensor data to be collected, aiding in continuum work of simulating the flow of these complex particle shapes Solution method: Double-send and double-receive communication was added to LIGGGHTS to allow for shared information across disjointed processor domains along the shearing boundary of the LEBC. The verification of this method is performed via 3D shearing simulations of single spheres and sphere clumps and rods with aspect ratios 2, 4, and 6. Additional comments including restrictions and unusual features: Code does not run unless it is parallelized across two (or more) processors in the Y-direction.