Linear stability analysis functionality #176
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Linear stability analysis is a prereq for reduced-order modeling and is also useful for validating flow configurations. This PR implements Arnoldi iteration with optional Krylov-Schur restart, including constructing shift-invert operators from a FlowConfig. Also adds scripts for stability analysis of the cylinder and cavity, which reproduce results in the reference papers.
There is also an experimental
LinearizedBDFtime-stepper, but I ended up going with shift-invert Arnoldi as a more efficient strategy than Krylov-Schur with time-stepping.Screenshots of direct and adjoint modes for the cylinder: