In this paper, we focus on the following general shape optimization problem:
\min\{J(\Om), \Om convex, \Om\in\mathcal S_{ad}\}, where Sad is a set of 2-dimensional admissible shapes and
J:Sad→R is a shape functional. Using a specific
parameterization of the set of convex domains, we derive some extremality
conditions (first and second order) for this kind of problem. Moreover, we use
these optimality conditions to prove that, for a large class of functionals
(satisfying a concavity like property), any solution to this shape optimization
problem is a polygon