Fine Structure and Regularity of Moving and Stationary Free Interfaces

forthcoming

Free boundaries and interfaces arise in problems in PDEs and Calculus of Variations, in which both the solutions and their domains are free to evolve in time. Several physical models and phenomena naturally lead to the formation of free boundaries and interfaces, for instance, phase-transition (the Stefan problems), periodic water waves (Stokes water waves), jet flows (the Bernoulli problems), tumor growth and congested crowd motion (Hele-Shaw flows), strong segregation (optimal partitions; harmonic maps). This project is dedicated to the analysis of the free interfaces from a purely theoretical point of view. The focus is on the Regularity Theory: starting from some very weak notion of solution and without making any a priori assumption on the shape and on the topology of its domain, we aim to describe the local structure of the free boundary and its evolution in time. Two phenomena will be central for the project: the formation of singularities in space and the persistence of these singularities in time. My main objective is to develop analytic methods for the description of the local structure of the free interfaces around such singularities. These results will have broad impact on the fields of PDEs and Geometric Analysis.