University of Birmingham > Talks@bham > Applied Mathematics Seminar Series > Variational problems involving rearrangements of functions

Variational problems involving rearrangements of functions

Add to your list(s) Download to your calendar using vCal

If you have a question about this talk, please contact Alessio Martini.

Joint Analysis / Applied Mathematics seminar

Two real functions on a domain in Euclidean space are said to be rearrangements of one another if they have the same decreasing rearrangement, that is, corresponding super-level sets of the two functions always have equal measure.

This concept from real analysis is also relevant to the dynamics of planar incompressible non-viscous fluids, because classically the curves of constant vorticity are convected with the flow and so the areas they enclose remain constant.

We will discuss rearrangements from an analyst’s wiewpoint, but with particular reference to problems from the Calculus of Variations where the set of all rearrangements of one fixed function forms the constraint. In fluids this corresponds to maximizing kinetic energy among “equivortical flows” and solutions represents steady vortices.

Existence of maximisers can be proved by means of convex analysis in conjunction with compactness properties of highly symmetric functions. In order to study stability one needs to prove compactness of all maximizing sequences, which may lack symmetry. This necessitates the use of concentration-compactness.

This talk is part of the Applied Mathematics Seminar Series series.

Tell a friend about this talk:

This talk is included in these lists:

Note that ex-directory lists are not shown.


Talks@bham, University of Birmingham. Contact Us | Help and Documentation | Privacy and Publicity.
talks@bham is based on from the University of Cambridge.