An immersed boundary fluid–structure interaction method for thin, highly compliant shell structures

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A parallel computational method for simulating fluid–structure interaction problems involving large, geometrically nonlinear deformations of thin shell structures is presented and validated. A compressible Navier-Stokes solver utilizing a higher-order finite difference immersed boundary method is coupled with a geometrically nonlinear computational structural dynamics solver employing the mixed interpolation of tensorial components formulation for thin triangular shell elements. A weak fluid–structure coupling strategy is used to advance the numerical solution in time. The thin shell structures are represented in the fluid domain by a geometry mesh with a finite thickness at or below the size of the local grid spacing in the fluid domain. The methodologies for load and displacement transfer between the disparate geometry and structural meshes are detailed considering a parallel computing environment. The coupled method is validated for canonical simulation-based test cases and experimental fluid–structure interaction problems considering large deformations of thin shell structures, including a shock impinging on a cantilever plate, a fixed cylinder with a flexible trailing filament in channel flow, a thin, clamped plate in wall-bounded flow, and a flag waving in viscous crossflow. The FSI method is then demonstrated on a compliant circular sheet with a clamped center exposed to crossflow and finally applied to the inflation of a spacecraft disk-gap-band parachute inflating in supersonic flow conditions resembling the upper Martian atmosphere, where comparison with experimental data is provided.