[petsc-users] Many issues solving matrix derived from a CFD coupled Solver

[Luca Mangani]

Good Morning,

After many steps I'm not able to solve my coupled matrix with iterative solver. The matrix is defined as the discretization of the Navier Stokes equation in a pressure based form. Also for a small case of 70K cells the linear solver blows up (GMRES(ILU BJACOBI) , BCGS(ILU BJACOBI)) and HYPRE+BOOMERAMG). For the boomerAMG I use this options:
  
-ksp_monitor_true_residual
-pc_type hypre
-pc_hypre_type boomeramg
-pc_hypre_boomeramg_max_iter 5
-pc_hypre_boomeramg_cycle_type V
-pc_hypre_boomeramg_relax_type_all SOR/Jacobi
-pc_hypre_boomeramg_grid_sweeps_down 3
-pc_hypre_boomeramg_grid_sweeps_up 0
-pc_hypre_boomeramg_grid_sweeps_coarse 3
-pc_hypre_boomeramg_rtol 0.0001
-pc_hypre_boomeramg_coarsen_type modifiedRuge-Stueben
-pc_hypre_boomeramg_relax_type_coarse SOR/Jacobi
-pc_hypre_boomeramg_interp_type multipass-wts
-ksp_max_it 60
-ksp_type richardson
-ksp_view
  
but without any success. That's really frustrating because of direct solvers are able to solve the matrix without any problem.

Do you have any suggestion of why can I have all this issues? Your help and support could be really appreciated.

Thanks in advance

Luca
  

-- 
Hochschule Luzern
Technik&  Architektur

Technikumstrasse 21, CH-6048 Horw
T +41 41 349 33 11, F +41 41 349 39 60

Maschinentechnik
CC Fluidmechanik und Hydromaschinen
Dr. Luca Mangani - PhD
Senior Research Fellow

T direkt +41 (0) 413493 248
luca.mangani at hslu.ch
www.hslu.ch/fmhm