Propulsive characteristics of dual fish-like foils

Abstract

The effect of the vertical and horizontal distances between dual fish-like foils on the propulsive characteristics of the biomimetic propulsor system is investigated by using an unsteady panel method. The present method is validated by comparing computed results with other numerical and experimental data. The mutual vortex-vortex interaction between the shed vortices from both foils has the effect of changing the pointing direction of mushroom heads. The leading foil’s propulsive characteristics do not change much with the vertical distance between the foils, whereas the following foil’s propulsive characteristics are changed significantly depending on the vertical and horizontal distances between the foils. The overall wake patterns depend mainly on the horizontal distance. The intensity of the mutual interaction between the wake vortices depends on the vertical distance. Thus, the propulsive characteristics of the dual fish-like foils are complicated functions of the vertical and horizontal distances between the foils. The present method has the limitation of potential-low assumption. If the flow separation near the leading edge of the foils is not significant, the present method can be applied to the design of biomimetic propulsors.