Abstract: The speed convergence algorithm is applied in the numerical simulation of a fishlike robot swimming straight forward. For an initial value given arbitrarily, the swimming speed is dynamically modified to converge to the steady value by verifying the thrust and drag forces during the swimming process. Numerical simulation of the hydrodynamic performance of the fishlike robot is carried out on the basis of the converged speed in order to reveal its propulsive mechanism and flow field structure. The results show that the steady-state swimming speed can be predicted effectively by using the speed convergence algorithm, while the thrust force, power consumption and propulsive efficiency can be obtained through varying the swing frequency and the maximum swing amplitude. The effects of positive pressure gradient and the adverse pressure gradient are clearly reflected in the 3-dimensional flow field structure around the robot. The numerical findings are of great significance to predicting the swimming speed, revealing the propulsive mechanism, and designing the motion parameters of fishlike robot.

Key words: Converged speed, Fishlike robot, Flow field structure, Propulsive mechanism, Speed convergence algorithm