Flow Control of Elastic Plates in Triangular Arrangement

The hydrodynamicinteractions in fish schooling is a complex problem and still not well understood. In this work we use three flexible plates arranged in triangular as the model to study hydrodynamics interactions in fish schooling.The immersed boundary-lattice Boltzmann method (IB-LBM) is used to implement the simulation. By varying the interval distance and the expansion angle of the three plats, the drag, lift and flapping pattern of them are analyzed. The simulation results show that all the plates could flap passively in stable period in our simulation conditions. The dominated flapping frequencies of the three plates are always equal. The two downstream plates will flap synchronously and have the same amplitude in most cases. The upstream plate has a strong influence on the downstream two. We demonstrate four typical flapping patterns of the three plates at different interval distances and the expansion angles. When the plates are close to each other enough, the dynamics of them are like a single plate. Drag decrease can be obtained at certain distance. When the distance is big enough, the interactions between the three plates can be ignored, the dynamic of each plate is the same with that of the single plate. This work may offer inspiration for understanding the hydrodynamic interactions of fish schooling and the underwater robots designing.