Two dimensional analysis of hydrodynamic performance of the fast swimming fish

Abstract

Two dimensional oscillating airfoil theory is used to estimate the thrust and propulsive efficiency generated by an idealized geometry and motions of the tail fin of a fast swimming fish. The present analysis is based upon the compact formulae developed by Garrick to evaluate the propulsion of a flat plate performing harmonic oscillations in two degrees of freedom. The thrust and propulsive efficiency are analyzed in functions of the reduced frequency, feathering parameter, and the position of pitching axis. Numerical examples are obtained and discussion about favorable conditions for the composite motion of the fish tail fin is followed.