Perfect fluid forces in fish propulsion: the solution of the problem in an elliptic cylinder co-ordinate system

This paper is a discussion of perfect fluid forces involved in fish propulsion. First, the two-dimensional problem is solved in elliptic cylinder co-ordinates in which the surface, or strip μ = 0 is used to approximate a ‘fish’. A travelling wave with linearly increasing ampli­tude is imposed on the strip to represent the motion of the fish. The problem then is in­vestigated for a rigid strip of finite width oscillating about the forward end. Results of this calculation are used to correct the general force expression to the case of low aspect ratio. Experimental results are then discussed which verify the validity of the calculations.