Numerical Study Relevant for Proper Design of Experiments on Swimming-fish Hydrodynamics

It has always been attractive for researchers to observeand understand the fish swimming behavior in water. Alarge number of real-fish tests has been carried out bybiologists in swim tunnels with the focus on estimatingaccurately fish metabolic rate. The space between the fishand boundary walls of the tunnel is often limited, leadingto potential wall effects on swimming performance fromhydrodynamic perspective. Besides, there have beenmany experimental and numerical studies on adeformable body fixed in its position in a uniform currentor tethered with the opposite velocity in a quiescent fluid.However, for the actual locomotion of the self-propelledfish, the undulatory deformation of the body might causerecoil reactions and then change the overall performance.This work aims to compare behaviors between a freeswimmingfish and a undulatory fish fixed in current, aswell as investigate the influence of the experimental setupon fish's hydrodynamic performance. Numericalsimulations have been carried out based on a two dimensionalfish-like foil. A self-propulsion function forflexible bodies has been implemented within theOpenFOAM library. As main results, the time-averagedforward swimming speed, fish locomotion and wakepatterns have been obtained and analyzed.