Fluid–structure interaction analysis on a flexible plate normal to a free stream at low Reynolds numbers

This paper presents a computational analysis of the fluid–structure interaction, especially for flexible structures. A flexible plate is placed normal to a free stream and the flow around it is simulated to investigate the effects of flexibility on the flow. The lattice Boltzmann method with an immersed boundary technique using a direct forcing scheme is used to simulate the fluid, and a finite element method with Euler beam elements is used to model the flexible plate. The direct forcing scheme of the lattice Boltzmann method is improved for the immersed boundary scheme by introducing the participation ratio of fluid lattices among the interpolated lattices. We compare the results of our proposed scheme with the known results of conventional schemes. Our results show that the flexibility of the plate significantly influences the reduction of the force coefficients induced by the flow. From the unsteady flow around the flexible plate, we find that the St of the flexible plate up to Re < 80 increase regardless of the plate flexibility, but the St in the range of Re > 120 is dependent on the plate flexibility. In the range of Re > 120 , the St of a very flexible plate increases with increasing Re, while the St of a rigid plate decrease with increasing Re.