Hydrodynamic analysis of fishlike robot swimming in the straight forward way

This paper investigates the three dimensional hydrodynamics of a fishlike robot swimming in the straight forward way under self-propulsion. The unsteady flow fields associated with swimming robot is computed by using Navier-Stokes equation. Both the user defined function and dynamic mesh technique are applied to track the robot motion. The results show that the mean magnitudes of net thrust force and net lift force approach to zero for one cycle. The variation trends of thrust force, swimming power and propulsive efficiency over time are in sine function. The computed flow fields clearly reveal the evolution of two pairs of pressure cores traveling along the robot as it swims. A positive pressure gradient around the tail is in competition with negative pressure gradient in the head; thrust forces is produced when the positive pressure gradient dominate the negative one. The findings help reveal the propulsive mechanism of the fishlike robot propulsion and benefit the fishlike robot design.