For a CFD panel-based potential method, I'm trying to reduce the time to solve the linear system. The matrix has the larger values on the diagonal, since the influence of a panel on itself is maximum, and that the panel's influence on other panels decreases at least as the inverse of their distance. The matrix has no reason to be diagonally dominant however.
GMRES converges nicely, perhaps due to the diagonal having the larger values. IS there a preconditioner that would make it even faster?