Abstract

For many years, fastest swimming speeds reported for dolphins are almost through observation. The principal objective of this study was to estimate the swimming speed of dolphin by simulating the thrust. Therefore, this paper primarily aimed to analyze the thrust characteristics of dolphins kick by numerical simulation, which used the FLUENT software solver and UDF dynamic mesh to simulate the dolphin during it is swimming. Three types of peak-to-peak tail motion amplitudes and frequencies are chosen to simulate. The simulation results of the thrust generated by dolphin fluke motion were compared with available data from the references. In conclusion, the dolphin can reach a very high speed and efficiency.

Introduction

For a long time, dolphins have always been considered as good swimmers with extremely high thrust efficiency and minimum resistance. There is still debate as to whether special properties of the skin itself contribute to the drag reduction or whether it is simply due to the maintaining of an attached turbulent boundary layer (Fish, 1993). Swimming encompasses the transfer of kinetic energy and momentum from the animal's propulsive movements to the water. High speeds allow increased foraging and active pursuit, but require large energy expenditures because thrust power is directly related to the cube of velocity. Low swimming speeds observed for cetaceans, while foraging and migrating (Lang, 1975; Fish, 1998a; Webb, 1975). A dolphin swimming at constant speed balances forces and moments acting on it by the principle of momentum conservation. The total thrust produced by the action of the caudal flukes balances the total resistance (i.e. drag) that the animal's body encounters moving forward (Fish and Rohr, 1999).

Nearly 2000 swimming-speed measurements were obtained from recordings of both captive and free-ranging dolphins. In all cases, some form of motivation was provided for the dolphins to swim fast. In the wild, dolphins swim over a wide range of speeds.

This content is only available via PDF.
You can access this article if you purchase or spend a download.