A three-phase fluid–structure interaction algorithm for compressible flows and thin-walled structures based on the extended ghost fluid method

Numerical simulations of fluid–structure interactions involving compressible fluids and thin-walled structures often encounter numerical oscillation issues. First, the numerical solution of two-phase flows with high density and pressure ratios suffers from discrete errors, which can induce nonphysical oscillations at the fluid–structure interaction interface. Second, the added mass effect causes a mismatch in wave impedance between the solid elastic wave and the fluid pressure wave, resulting in the continuous back-and-forth propagation of elastic waves within the thin-walled structure. This induces nonphysical oscillations at the fluid–structure interaction interface. This study proposes a three-phase fluid–structure interaction algorithm based on the extended ghost fluid method to effectively eliminate these numerical oscillations. First, the fifth-order weighted essentially nonoscillatory finite difference method is employed to solve the flow of compressible two-phase fluids. Meanwhile, the finite element method is used to solve the motion of thin-walled structural deformations. Subsequently, the ghost fluid method is extended and enhanced for application to interactions between compressible fluids and thin-walled structures. Meanwhile, coupling rules between fluid grid nodes and solid hexahedral finite elements are established to effectively mitigate nonphysical oscillations. Comparisons between numerical and experimental results, the numerical accuracy at the fluid–structure interface, and the mass conservation in the fluid domain collectively demonstrate that the extended ghost fluid method, combined with the proposed fluid–structure coupling rules, is robustly applicable to simulations involving compressible flows and thin-walled structures.