Von Karman Vortices
In the first example of Von Karman Vortices, a heated plate with a thick initial thermal boundary layer is suddenly accelerated to 5 m/s in air. The thermal boundary layer is swept downstream and rolls up into a pair of shed vortices. Temperature contours are shown in the movie making the flow visible. The Reynolds number of the flow is 200,000, well beyond the critical Reynolds number of 40 where vortex shedding begins. Thus the wake region is unstable and breaks up into a Von Karman vortex street. Vortex shedding from a rectangular bar is demonstrated in the second example . The periodic nature of the Von Karman vortex street is best illustrated in the third example, which shows the vortex street created by a flat plate. This movie only includes a single cycle of the phenomenon, therefore for best viewing, configure your MPEG viewer to play the movie in a continuous loop.