An open-source, four-way coupling, adaptive solver for particle-resolved simulation with hybrid parallelization

We present the IAMReX, an adaptive solver for particle-resolved simulation with hybrid MPI and OpenMP parallelization. The fluid equations are solved using a finite-volume scheme on the blocked structured semi-staggered grids with both subcycling and non-subcycling methods.~The interaction between and fluid and particle is resolved using the multidirect forcing immersed boundary method. The associated Lagrangian markers used to resolve fluid-particle interface only exist on the finest-level grid, which greatly helps to save the memory usage. The volume integrals are numerical calculated to accurately capture the free motion of particles, and the repulsive potential model is also included to account for the particle-particle collision. We demonstrate the versatility, accuracy, and efficiency of the present subcycling multilevel framework by simulating fluid-particle interaction problems with various types of kinematic constraints. The source code and testing cases used in this work can be accessed at~\url{https://github.com/ruohai0925/IAMR/tree/development}. All input scripts and raw postprocessing data will be added later.