Simulation of fluid−flexible structure interaction

Systems involving flexible bodies interacting with surrounding fluid flow are commonplace, but are challenging to model numerically on account of their complex geometries and freely moving boundaries. In the present study, we developed an immersed boundary method (IB) for simulating fluid−flexible structure interactions. Our method is based on an efficient Navier-Stokes solver adopting the fractional step method and a staggered Cartesian grid system. The fluid motion defined on an Eulerian grid and the structure motion defined on a moving Lagrangian grid are independently solved, and their interaction is formulated using a momentum forcing. The proposed method was applied to simulating flow over flexible filaments with inextensibility constraint, and was then extended to simulate 3D flag motion in a uniform flow. Toward bio-mimetic applications, we also simulated a valveless pump and an energy harvesting eel by utilizing the 1D filament model, and a swimming jellyfish and a deformable disk by utilizing the 2D structure model.