Study of 3D self-propulsive fish swimming using the δ+-SPH model

The bio-inspired propulsion facilitates the design of underwater vehicles because it benefits both the hydrodynamic performance and endurance of the underwater robots. This work is dedicated to investigating the fluid-structure interaction (FSI) of a three-dimensional (3D) self-propulsive anguilliform swimmer using the smoothed particle hydrodynamics (SPH) method. To this end, the delta(+)-SPH model incorporating with the techniques of tensile instability control (TIC) and adaptive particle refinement (APR) is adopted. Firstly, to validate the accuracy and stability of the present SPH model, viscous flows past 3D sphere are simulated and validated. After that, the 3D fish-liking swimming problem is simulated and the velocity of body center is compared with the reference result. Further, the comparison of the two-dimensional (2D) and 3D self-propulsive swimming problem shows that the longitudinal velocity and vorticity field are in large discrepancy. In addition, the vortex structure of the 3D fish's wake is visualized and discussed in detail. It is demonstrated that the present 3D delta(+)-SPH model can be regarded as a reliable approach to investigate such bionic hydrodynamic problem close to a real fish.