[petsc-users] Preconditioner for stokes flow with mixed boundary conditions.

[Abhinav Singh]

Hello all,

I am trying to solve for incompressible stokes flow on a particle based
discretization. I use a pressure correction technique along with Particle
strength exchange like operators.

I call Petsc to solve the Stokes Equation without the pressure term. GMRES
usually works great but with dirichlet boundary conditions. When I use a
mixed boundary condition in Y, (dirichlet on bottom and Neumann on the top)
with periodicity in X,Z. GMRES fails converge when the size of matrix
increases. For smaller size (upto 27*27*5), only GMRES works and that too
only with the option 'pc_type none'. I was unable to find any
preconditioner which worked. Eventually, it also fails for bigger size.
UMFPACK works but LU decomposition fails after a certain size and is very
slow.

It would be great if you could suggest a way or a preconditioner which
suits this problem.

Kind regards,
Abhinav
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