A PARTITIONED FLUID-STRUCTURE INTERACTION INTERFACE EQUILIBRIUM METHOD AND ITS APPLICATION IN STRONG ADDED MASS PROBLEMS

The implicit finite volume/explicit finite element partitioned fluid-structure interaction (FSI) method combines the advantages of implicit fluid solvers in terms of large time steps and numerical stability with the computational accuracy and robustness of explicit solid solvers in handling large deformations and nonlinear dynamic problems, thereby holding broad application prospects in multi-physics partitioned coupling. However, under strong added mass effects, traditional partitioned FSI methods often suffer from numerical instability issues. Particularly when explicit finite element solvers are employed for the solid domain, their small time steps and high-frequency velocity oscillations significantly amplify interface errors, leading to difficulties in convergence. To address this critical challenge, this paper proposes a partitioned implicit finite volume/explicit finite element computational framework tailored for strong added-mass scenarios. The method introduces displacement-velocity-force three-field consistency constraints into the interface conditions, effectively resolving the issue of traditional displacement-force two-field coupling failing to ensure interface velocity balance. Simultaneously, by incorporating a coupled time window control mechanism and high-precision mapping based on radial basis functions, the accuracy of data transfer and the stability of the coupling process are enhanced. Validation through pressure-driven elastic tube expansion and the Turek-Hron FSI3 benchmark cases demonstrates that the proposed method achieves stable and convergent results even under strong added mass conditions, with significantly reduced interface oscillations. The structural displacements and oscillation frequencies show high consistency with reference solutions. In addition, based on the above benchmark cases, the coupled computational efficiency of the proposed improved algorithm is analyzed. The results indicate that, compared with the conventional algorithm, the total coupled time required by the improved algorithm to complete the calculations is reduced by 73.4% and 89.0%, respectively. Consequently, the coupling strategy presented in this paper effectively overcomes the instability associated with explicit solvers in coupled simulations, enabling stable and high-precision computation of FSI problems under strong added mass effects.