A multigrid partition coupled Eulerian-Lagrangian method for fluid-solid interaction problems

In this paper, a multigrid partition coupled Eulerian-Lagrangian method (PCELM) is proposed to model fluid-solid interactions between fluids and moving or fixed rigid bodies. In this method, Lagrangian particles are arranged in Eulerian grids to track the interface, and the partition weighted bidirectional mapping method is used to improve the mapping accuracy between particles and grids. The multigrid domain is established to realize independent and contact calculations of the fluid and solid, which can solve for the cross-interference of multiple velocity fields in a single grid domain. Moreover, based on the contact in the particle volume domain, a more accurate fluid-solid interaction method, in which the contact properties of real grid nodes are identified by judgment and search criteria and then corrected, is proposed to overcome false contact and nonphysical penetration problems. Then, the accuracy and stability of the PCELM are verified using representative fluid-solid interactions. Finally, experiments and simulations of dam-break floods impacting the dam board are carried out. These experiments prove that the PCELM can accurately capture the free surface of dam-break floods and can provide suggestions for the installation of dam boards in hydraulic engineering.