On the high-performance swimming of a tuna-inspired underwater vehicle Part II: Computational analysis*

High-fidelity flow simulations are used to examine the key hydrodynamic features and thrust performance of the tuna-inspired underwater vehicle (TunaBot) swimming at a constant forward velocity. The numerical modeling approach employs a sharp-interface immersed-boundary-method (IBM)-based incompressible flow solver with adaptive mesh refinement (AMR) method. The three-dimensional, time-dependent kinematics of the body-fin system of the TunaBot is obtained via a stereo-videographic technique. The computational model is then directly reconstructed based on the experimental data with remarkably high accuracy. The primary objectives of the computational effort are to quantify the thrust performance of the TunaBot at different Reynolds number as well as to establish the mechanisms responsible for thrust production. Simulations show that the bending angle and bending rate of the TunaBot’s caudal peduncle play important roles in thrust producing. A distinct system of connected vortices produced by the TunaBot is also examined in detail for understanding the thrust producing mechanism.