Experimental hydrodynamics imaging and undulatory movement equation of steady swimming fish (Pangasius sanitwongsei)

Abstract

This paper presents a quantitative characterization of caudal fin. Steady swimming of Pangasius sanitwongsei was studied experimentally and taped by high speed digital video and undulatory movement of fish was revealed. As a result, an experimental equation was found. This equation indicates that, as much as the ratio of the end part of fish with high undulatory movement (body and caudal fin) to the total length goes up, the ratio of amplitude to the total length increases. Consequently, displacement increases and thrust force increases too. Then undulatory movement equation of fish swimming was calculated by fitting a second order function which describes wave amplitude of this type of fish. All the findings in these researches could be applied to design a robotic fish.