Overdetermined elliptic problems in onduloid-type domains with general nonlinearities

Abstract

In this paper, we prove the existence of nontrivial unbounded domains omega subset of Rn+1, n >= 1, bifurcating from the straight cylinder BxR (where B is the unit ball of R-n), such that the overdetermined elliptic problem {delta u + f(u) = 0 in omega, u = 0 on & part;omega, & part;(nu)u = constant on & part;omega, has a positive bounded solution. We will prove such result for a very general class of functions f: [0, + infinity) -> R. Roughly speaking, we only ask that the Dirichlet problem in B admits a nondegenerate solution. The proof uses a local bifurcation argument.