Multiphysics Implicit Coupling Method for Fluid, Particles, and Large-Deformation Structures

This study presents an implicit multiphysics coupling method integrating Computational Fluid Dynamics (CFD), the Multiphase Particle-in-Cell (MPPIC) model, and the Finite Element Method (FEM), implemented with OpenFOAM, CalculiX, and preCICE to simulate fluid-particle-structure interactions with large deformations. Mesh motion in the fluid field is handled using the radial basis function (RBF) method. The particle phase is modeled by MPPIC, where fluid-particle interaction is described through momentum exchange, and inter-particle collisions are characterized by collision stress. The structural field is solved by nonlinear FEM to capture large deformations induced by geometric nonlinearity. Coupling among fields is realized through a partitioned, parallel, and non-intrusive iterative strategy, ensuring stable transfer and convergence of interface forces and displacements. Notably, the influence of particles on the structure is not direct but mediated by the fluid, while structural motion directly affects particle dynamics. The results demonstrate that the proposed approach effectively captures multiphysics interaction processes and provides a valuable reference for numerical modeling of coupled fluid-particle-structure systems.