Krylov Methods for the Incompressible Navier-Stokes Equations

Methods are presented for time evolution, steady-state solving and linear stability analysis for the incompressible Navier-Stokes equations at low to moderate Reynolds numbers. The methods use Krylov subspaces constructed by the Arnoldi process from actions of the explicit Navier-Stokes right-hand side and of its Jacobian, without inversion of the viscous operator. Time evolution is performed by a nonlinear extension of the method of exponential propagation. Steady states are calculated by inexact Krylov-Newton iteration using ORTHORES and GMRES. Linear stability analysis is carried out using an implicitly restarted Arnoldi process with implicit polynomial filters. A detailed implementation is described for a pseudospectral calculation of the stability of Taylor vortices with respect to wavy vortices in the Couette-Taylor problem.