On 3D instabilities of 2D time-periodic flows

Juan M. Lopez
Department of Mathematics & Statistics
Arizona State University


We consider how time-periodic 2D flows may become unstable to 3D 
perturbations. The Karman vortex street, the 2D periodically shedding wake 
of a circular cylinder, is the prototypical example. We shall consider 
this as well as a periodically forced enclosed flow as examples to 
illustrate the abstract problem in equivariant bifurcations describing the 
2D to 3D transitions. The talk will present results from normal form 
analysis, Floquet stability analysis, computations of the 3D Navier-Stokes 
equations, and laboratory experiments.