ring of vorticity

Twodimensional simulation of a ring of vorticity (colorfilled contours).

Stream function (dashed white contours) is calculated from vorticity with
a direct solution of the Poisson equation.

Velocity is calculated from the stream function. A thirdorder upwind scheme is used to advect vorticity.

Computation with Python and numpy.

1025×1025 grid points

The initial ring is set slightly offcenter so that the perturbation is not purely
a wave number 4.