Propulsive Performance of Dolphins —Estimation from Analysis of Standing Swimming

In the standing swimming of dolphins, which is often seen in aquariums, the total weight of the body is supported by the caudal fin in the water. It is clear that the thrust generated by the fanning motion of the caudal fin is equal to the body weight. In the study reported in this paper, a numerical simulation of the flow around the caudal fin (of the bottlenose dolphin) using the three-dimensional Navier-Stokes (3D NS) code for the standing swimming condition is conducted and the necessary power is computed. The power thus determined is approximately three to four times larger than the power necessary for the cruising swimming condition, determined by the performances observed to date for trained dolphins in aquariums. With this necessary power, we estimate the maximum speed the dolphin can attain, using the 3D modified doublet lattice method coupled with an optimum design method and the 3D NS code, obtaining a value of approximately 13 m/s, which is considerably higher than values observed in aquariums.