understanding the output from -info

[Ben Tay]

Hi,

I have some questions regarding the use of hypre/boomeramg:

1. Is there anything I need to change in the assembly of matrix etc besides
adding  -pc_type hypre -pc_hypre_type boomeramg ?

2. Can it work in a sequential code?

3. I have 2 eqns to solve - momentum and poisson. if I used the options,
will both equations be solved using hypre? Can I select which solver to
solve with which equation?

Thank you.


On 2/12/07, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>
> hypre/boomeramg may be the way to go, especially for the Poisson
> problem. -pc_type hypre -pc_hypre_type boomeramg (-help for lots of
> tuning options.).
>
>   Barry
>
>
> On Sun, 11 Feb 2007, Ben Tay wrote:
>
> > Well,
> >
> > I am simulating unsteady flow past a moving airfoil at Re~10^4. I'm
> using
> > fractional step FVM, which means that I need to solve a momentum and
> poisson
> > equation.
> >
> > To reach a periodic state takes quite a few hours and so I'm trying to
> find
> > ways to speed up the process. I thought parallelizing the code would
> help
> > but it seems like it's not the case.
> >
> > I'm now trying out different types of solver/preconditioner available on
> > PETSc to assess their performance. Is there other external solvers,
> which
> > PETSc interfaces, which are recommended? I'm thinking of using multigrid
> to
> > solve the poisson eqn... wonder if hypre/BoomerAMG etc would help...
> >
> >
> > On 2/11/07, Lisandro Dalcin <dalcinl at gmail.com> wrote:
> > >
> > > On 2/10/07, Ben Tay <zonexo at gmail.com> wrote:
> > > > In other words, for my CFD code, it is not possible to parallelize
> it
> > > > effectively because the problem is too small?
> > > >
> > > > Is these true for all parallel solver, or just PETSc? I was hoping
> to
> > > reduce
> > > > the runtime since mine is an unsteady problem which requires many
> steps
> > > to
> > > > reach a periodic state and it takes many hours to reach it.
> > >
> > > Can you describe your specific application and how are you solving it?
> > > As Barry said, your need-for-speed is not likely to be solved by
> > > running in parallel.
> > >
> > >
> > > --
> > > Lisandro Dalcín
> > > ---------------
> > > Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
> > > Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
> > > Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
> > > PTLC - Güemes 3450, (3000) Santa Fe, Argentina
> > > Tel/Fax: +54-(0)342-451.1594
> > >
> > >
> >
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