Numerical simulation of interaction between multiphase flows and thin flexible structures

We develop a fluid–structure interaction numerical algorithm based on the immersed boundary (IB) method for simulating the interaction between air–water two-phase flows and thin flexible structures. In this algorithm, we propose a new method to avoid the unphysical fluxes across the thin structures, which effectively mitigates the issue of flow spurious penetration. In the proposed method, an explicit pressure boundary condition on the immersed boundary is applied. A new scheme for categorizing fluid, solid, and forcing nodes in the IB method is developed for avoiding extra pressure interpolation at the velocity projection step of the fractional-step method. The fluid motions are solved by a finite difference method. A coupled level-set and volume-of-fluid method is implemented to capture the free interface. A finite element method is utilized to solve the deformation of flexible plates. Two benchmark cases are tested and good agreement with the results in the literature is obtained.