Special Session 149: Recent developments in Free Boundary Problems and Nonlinear PDEs

A Free Boundary Problem with Nonlocal Obstacle
Hayk Mikayelyan
University of Nottingham Ningbo China
Peoples Rep of China
Co-Author(s):    M. Chipot, Zh. Lin
Abstract:
We consider a functional with with the nonlocal obstacle acting on the function $V(x')=\int_0^1 U(x', t) dt $ $$ \int_\Omega \frac{1}{2}|\nabla U(x)|^2dx +\int_D V(x')^+\,dx'. $$ The minimizer solves the equation $$ \Delta U(x',x_n) = \chi_{\{V>0\}}(x') + \chi_{\{V=0\}}(x') [\partial_\nu U (x',0) + \partial_\nu U (x',1)], $$ where $\partial_\nu U$ is the exterior normal derivative of $U$. Several regularity results are proven. It is shown that the comparison principle does not hold for minimizers, which makes numerical approximation we present somehow challenging.