Solitary vortex pairs, diwhirls
A snapshot of Taylor column with solitary vortex pairs, diwhirls (Groisman and Steinberg, PRL 97) The flow was visualized by light reflecting Kalliroscope flakes in ambient light. The stationary outer cylinder was transparent, the rotating inner cylinder was black. The randomly spaced rings correspond to cores of the diwhirls, where there is a strong radial flow inwards. The background flow is the laminar shear Couette flow.