Numerical Simulation Method for Fluid–Structure Interaction of Deformable Structures Based on Multibody Dynamics

With the development of morphing aircraft, understanding the fluid–structure interaction (FSI) mechanisms of multibody systems composed of rigid and flexible components has become increasingly important. The coupled motion and deformation of such systems in a flow field give rise to complex nonlinear FSI problems. Here, we propose a fluid–multibody–structure interaction framework that couples a finite volume Navier–Stokes solver, a multibody dynamics solver, and radial basis function interpolation for fluid–structure data transfer. The framework is validated using a benchmark case and subsequently applied to simulations of a two-segment flexible beam and a three-dimensional continuously variable-sweep wing. The results show that the presence of joints and structural flexibility substantially affects the FSI response: hinge location markedly alters the FSI characteristics of the multibody flexible-beam system, while increasing the sweep angle during continuous morphing reduces the aerodynamic force coefficients and structural flexibility induces persistent fluctuations in aerodynamic loads. A key contribution of the proposed framework is its ability to capture both active morphing motions and passive aeroelastic deformations simultaneously. Compared with approaches based on inviscid, incompressible aerodynamic models, the present high-fidelity flow solver can better resolve complex flow phenomena during morphing. This framework provides a useful numerical tool for investigating FSI mechanisms in morphing aircraft. Its current limitations include the computational cost of global radial basis function interpolation for large multibody systems and its applicability being restricted to low-Mach-number flows.