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Old   September 28, 2008, 02:52
Default AMG in hypre
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AMG
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Dose anybody use AMG in hypre to solve fluid flow? I would appreciate your comment.

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Old   September 29, 2008, 05:18
Default Re: AMG in hypre
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Jed
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Yes, I use it as the velocity preconditioner in a coupled solver for incompressible flow of power-law fluids. I use it through the PETSc interface and have found ML to frequently be more performant and use less memory, although the robustness of BoomerAMG seems to be better. What do you want to do.
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Old   September 29, 2008, 08:00
Default Re: AMG in hypre
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AMG
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Thanks! I want to use it solve incompressible flow in a general unstructured fluid solver. I would appreciate your suggestions.
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Old   September 29, 2008, 08:24
Default Re: AMG in hypre
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Jed
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I would recommend interfacing to PETSc instead of directly to BoomerAMG since it will be much easier to try alternatives like ML (everything becomes a command-line argument). Do you want a coupled solver or do you use projection methods? If you are solving the coupled equations, you may be interested in some Schur-complement preconditioning which is available in petsc-dev (http://www-unix.mcs.anl.gov/petsc/pe...ers/index.html) but not yet in the released version.

I am not aware of any publicly available parallel algebraic multigrid package for indefinite problems. There has been some success with Vanka smoothers, but the standard method is to use Schur complement preconditioning where multigrid is used as a preconditioner for the velocity block. Good references below.

@article{benzi2005nss, title={{Numerical solution of saddle point problems}}, author={Benzi, M. and Golub, G.H. and Liesen, J.}, journal={Acta Numerica}, volume={14}, pages={1--137}, year={2005}, publisher={Cambridge Univ Press} }

@article{deniet2007tps, title={{Two preconditioners for saddle point problems in fluid flows}}, author={de Niet, AC and Wubs, FW}, journal={Int. J. Numer. Meth. Fluids}, volume={54}, pages={355--377}, year={2007} }

@article{kay2002pss, title={{A preconditioner for the steady-state Navier-Stokes equations}}, author={Kay, D. and Loghin, D. and Wathen, A.}, journal={SIAM Journal on Scientific Computing}, volume={24}, number={1}, pages={237--256}, year={2002}, publisher={SIAM} }
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Old   June 5, 2009, 18:35
Default Hypre
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ahnav is on a distinguished road
Hi every one !
I have a human head model. Simulation of this model generates large sparse symmetric positive definite matrices,
in the form of Ax = b.
Now I have matrices A as large as 1 gb, and same is the vectors b.
I would like to use Hypre for solving linear equation, any one who is familiar with hypre and its use. I have these questions.
1 - What can be the best way to solve my matrix A and vector b which has values from my simulations, using PCG of Hypre library.
2 - I want to solve this equation on many processors say more than 100, which can be the optimal approach.
I'll be really grateful for your replays.
BRs.
Ahnav
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