Comparison of performance of iterative methods for singular and nonsingular saddle point linear systems arising from Navier–Stokes equations

We compare the convergence performance of iterative methods for solving singular and nonsingular linear systems arising from discretization and linearization of the steady-state Navier–Stokes equations. With a combination of analytic and empirical results, we study the effects of singularity and nonsingularity on convergence. We will show that the convergence performance for solving a singular linear system is better than that for solving a nonsingular linear system.