University of Toronto PDE/Applied Math/Analysis Seminar Friday 26 September, 12:10-1:00pm 6183 Bahen Center SPEAKER: Marianne Korten TITLE: On the Stefan and Hele-Shaw problems with a degenerate phase ABSTRACT: In this talk I will survey new results about parabolic free boundary problems with a degenerate phase connected to Stefan problems. The first one establishes the Rankine-Hugoniot condition at "most" points of the free boundary in the one phase Stefan problem under minimal smoothness assumptions (joint work with Donatella Danielli). The second one establishes intrinsic energy estimates for the temperature in the two phase Stefan problem (which are more delicate to obtain as one is working with signed solutions). Immediate applications are explicit expressions for the free boundary measures, leading to an existence theorem for the two-phase Stefan problem when initial data are signed measures (joint work with Chuck Moore). Next I will describe complete existence and uniqueness results for the Hele-Shaw problem in higher dimensions with a degenerate phase, which hold even for a non-simply connected injection slot. These results cover both Dirichlet and Neumann boundary data and include classical results under enough regularity. Under standard assumptions we obtain regularity results for the free boundary (joint work with Ivan Blank and Chuck Moore). ------------------------------------------------------------------ University of Toronto PDE/Applied Math/Analysis Seminar http://www.math.toronto.edu/appmath/ 2006-2007 organizers: Pieter Blue pblue@ math.toronto.edu Almut Burchard almut@ math.toronto.edu Robert McCann mccann@ math.toronto.edu ------------------------------------------------------------------