On the eigenvalues of the biharmonic operator on annuli
Davide Buoso, Riccardo Molinarolo
Published: 2025/10/6
Abstract
We show that the fundamental tone of the bilaplacian with Dirichlet or Navier boundary conditions on radially symmetric domains is always simple in dimension $N\ge3$. In dimension $N=2$ we show that it is simple if the inner radius is big enough.