Do you know any methods/solvers for PDE or eigenvalue problems like
- $\begin{cases} \Delta u= 0\ (\text{ or }\lambda u) & \text{ in }\Omega \\ u =0 & \text{ on }\partial \Omega \end{cases}$ (Dirichlet)
- $\begin{cases} \Delta u= 0\ (\text{ or }\lambda u) & \text{ in }\Omega \\ \frac{\partial u}{\partial n} =0 & \text{ on }\partial \Omega \end{cases}$ (Neumann)
- $\begin{cases} \Delta u= 0\ (\text{ or }\lambda u) & \text{ in }\Omega \\ \frac{\partial u}{\partial n}+\beta u =0 & \text{ on }\partial \Omega \end{cases}$ (Robin)
in 2D and 3D that do not involve the Finite Element Method?
In 2D there is at least an option (for Dirichlet and Neumann): mpspack which uses a basis for the space of harmonic functions and works only with coefficients in this basis. In 3D I do not know anything that doesn't use Finite Element Method.
I am interested in a different method than FEM because in shape optimization domains change at every iteration and so does the mesh, the discretization, etc.