A fluid–structure interaction numerical simulation was performed to investigate the flow field around a flexible flapping wing using an in-house developed computational fluid dynamics/computational structural dynamics solver. The three-dimensional (3D) fluid–structure interaction of the flapping locomotion was predicted by loosely coupling preconditioned Navier–Stokes solutions and non-linear co-rotational structural solutions. The computational structural dynamic solver was specifically developed for highly flexible flapping wings by considering large geometric non-linear characteristics. The high fidelity of the developed methodology was validated by benchmark tests. Then, an analysis of flexible flapping wings was carried out with a specific focus on the unsteady aerodynamic mechanisms and effects of flexion on flexible flapping wings. Results demonstrate that the flexion will introduce different flow fields, and thus vary thrust generation and pressure distribution significantly. In the meanwhile, relationship between flapping frequency and flexion plays an important role on efficiency. Therefore, appropriate combination of frequency and flexion of flexible flapping wings provides higher efficiency. This study may give instruction for further design of flexible flapping wings.
Overlapping additive Schwarz preconditioners for elliptic PDEs on the unit sphere
