Motion of an elliptical uniform vortex outside a circular cylinder

The two-dimensional motion at infinite Reynolds number of an elliptical, uniform vortex outside a circular cylinder is investigated. The analysis is performed under the main assumption that the vortex generation at the wall can be neglected: the boundary layer reduces to a vortex sheet lying on the body wall. The flow is invariant under rotations around the body, so that the system possesses three degrees of freedom and two first integrals of the motion are known. A qualitative analysis of the motion is carried out in a suitable phase plain and comparisons with numerical simulations are also discussed.