FCM-FEM hybrid scheme equipped with a ghost element coupler for liquid–gas–solid three phase simulation

This study presents a liquid–gas–structure interaction analysis method equipped with a new coupler. The finite cover method (FCM) is employed for the Eulerian analysis of liquid–gas two-phase flows, and the Lagrangian finite element method (FEM) is used for the structural analysis of largely deformed structures. The concept of finite covers is introduced to track the boundaries of structures moving within an Eulerian mesh of liquid and gas phases, while the gas-liquid boundary is implicitly captured by the phase-field model. Furthermore, in addition to combining analytical methods that are suitable for fluid and solid phase problems, the highlight of the proposed method is a new coupler called the “ghost element coupler”, which uses ghost elements extended from the solid domain to the fluid side to evaluate the interaction forces on the moving boundaries of structures. Variable exchange between the fluid and structural domains is achieved by implementing an iterative partitioned method with dynamic relaxation in a strongly coupled manner. The effectiveness and accuracy of the proposed FCM-FEM hybrid scheme are verified by numerical examples of a series of benchmark problems.