Vortex Dynamics#
Concentrate all of a flow’s vorticity into a handful of points and the Navier-Stokes equations collapse to ordinary differential equations: each point vortex simply drifts in the velocity field induced by every other one. The examples below show how differently two vortices behave depending only on the relative sign of their circulation – a rigid, orbiting pair if the signs match, a self-propelling dipole that runs off in a straight line if they don’t – and then scale that same Biot-Savart mechanics up to a full von Karman street, the staggered double row shed behind every bluff body from a chimney to a violin string in the wind. Watch how the street holds its staggered spacing intact at von Karman’s stable ratio, in stark contrast to the pairwise dynamics of the first example.
