Hydrodynamics of Thunniform Swimming: Self-propelled Large-Eddy Simulations

The effects of Reynolds Number on a self-propelled virtual tuna are investigated using Large-Eddy Simulation Curvilinear Immersed Boundary (LES-CURVIB) method. The kinematics of the swimmer are prescribed based on experimental observations provided by the Hopkins Marine Station at Stanford University. Simulations are performed at the biologically relevant Reynolds Number (Re) of 1.1 million and artificial lower ones of 4000 and 40000. Wall-resolved LES has been performed for Re = 40000 and log-law wall model has been used for Re = 1.1 million. The simulations show that the Froude efficiency of the swimmer is much higher at the biological Re compared to the intermediate and lower Re. A leading-edge vortex has been observed on the tail which increases the thrust generation by generating a reduced pressure region at the leading edge.