A CFD-FEM-IBM simulation scheme for the strong coupling between the fluid and the structure with large deformations and movements

To describe the strong coupling between the fluid and the elastic structure with drastic deformations and large movements, a CFD-FEM-IBM simulation scheme is proposed. The fluid dynamics are governed by the Navier-Stokes equations, while the highly nonlinear mechanical behavior of the deformable structure is simulated using the updated Lagrangian incremental description. An outstanding feature of the hybrid method is that both the computational fluid dynamics and the computational solid dynamics are discretized spatially in the finite element framework. Besides, the main challenge in simulating strong coupling effects accurately lies in describing the fluid–structure boundary which deforms drastically over time. The direct-forcing immersed boundary method is employed to tackle the fluid–structure interaction and immersed boundary points allocated on the deformable surface of the structure are used to represent the fluid–structure interface. Both the no-slip boundary condition and the divergence-free condition for the IBM are ensured thorough several iterations. Moreover, the partitioned approach is utilized to solve the coupling system and iterations are carried out at each time step to reflect strong coupling effects. The reliability and accuracy of the current method in simulating the fluid–structure interaction problems with large deformations and movements are finally validated by benchmark tests.