WI-USHER: A grid-based parallel algorithm for particle insertion in hybrid atomistic-continuum method

Abstract

The hybrid atomistic-continuum coupling method based on domain decomposition serves as an important tool for the micro-fluid simulation. There exists a certain degree of parallelism load imbalance when directly using the USHER algorithm in the domain decomposition–based hybrid atomistic-continuum coupling method. In this article, we propose a grid-based parallel algorithm for particle insertion, named WI-USHER, to improve the efficiency of the particle insertion operation when restricting the size of the region to be inserted or with higher number density. The WI-USHER algorithm slices the region to be inserted into finer grids with proper spacing scale, marks parts of finer grids in black according to three exclusive rules, that is, Single Particle Occupation (SPO), Single Particle Coverage (SPC), and Multi-Particles Coverage (MPC), and finds the target insertion point in the remained white grids. We use two test cases to show the superiority of our WI-USHER algorithm over the USHER algorithm. The WI-USHER algorithm performs lower averaged force evaluation times, which decreases from O ( 10 4 ) to O ( 10 3 ) compared to the USHER algorithm when the number density of slightly high to high value. The percentage of the total parallel simulation time processed by the particle insertion operation decreases from 23.5% to 3% compared to the USHER algorithm.