Dear @prj ,
I just realized that when I am solving my linear system with reusing the LU factorization (discussed in this topic, I am not using the option -ksp_initial_guess_nonzero true option, with which the solution time can be reduced even further. However, when I am trying to switch on and off -ksp_initial_guess_nonzero similarly to ksp_reuse_preconditioner, I get a strange error message
[0]PETSC ERROR: Running KSP of preonly doesn’t make sense with nonzero initial guess
you probably want a KSP type of Richardson
I also made an MWE which reproduces this behavior with some small modifications to the Stokes-PETSc example. Could you please take a look at this, and suggest a possible solution to this problem?
stokes-2d-PETSc.edp (1.6 KB)
Thanks
András