Hydrodynamics of Fish-Shaped Rigid Bodies: Velocity-Drag Coupling

This study provides insights into the mechanisms of drag generation on fish-shaped bodies in turbulent open-channel flows. We conducted a set of experiments with rigid 3D-printed models of rainbow trout (Oncorhynchus mykiss), recording velocities upstream and downstream of a model along with drag force. For a range of fish Reynolds numbers, we have (1) assessed mean values of drag and drag coefficients, and (2) investigated drag force fluctuations and their link with upstream undisturbed turbulence. Correlation functions confirm a direct link between upstream velocity fluctuations and drag force fluctuations, although other mechanisms contributing to drag force fluctuations are likely and remain to be studied further. Insights into the hydrodynamics of fish-shaped bodies may lead to improvements in the design of fish passageways.