Mixing in fluid flow

Job Candidate Talk
Thursday, January 24, 2013 - 11:00am for 1 hour (actually 50 minutes)
Skiles 006
Alexander Kiselev – University of Wisconsin, Madison – http://www.math.wisc.edu/~kiselev/
Zhiwu Lin
Mixing by fluid flow is important in a variety of situations in nature and technology. One effect fluid motion can have is to strongly enhance diffusion. The extent of diffusion enhancement depends on the properties of the flow. I will give an overview of the area, and will discuss a sharp criterion describing a class of incompressible flows that are especially effective mixers. The criterion uses spectral properties of the dynamical system associated with the flow, and is derived from a general result on decay rates for dissipative semigroups of certain structure. The proofs rely on methods developed in studies of wavepacket spreading in mathematical quantum mechanics.