Rotational Inviscid Flow in a Variable Area Annulus, Pipe or Channel

Theoretical and experimental results concerning rotational inviscid flow in an annulus, pipe or channel of variable cross-section are given. Vorticity and continuity considerations are used to determine the velocity profile downstream from the variable area portion in terms of the velocity profile upstream. The lengthening or shortening of vortex lines alters the vorticity in the flow. Regimes of possible reverse flow and flow separation are obtained. The agreement between the theory and experiment is good.