<div>Hi,</div>
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<div>I have some questions regarding the use of hypre/boomeramg:</div>
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<div>1. Is there anything I need to change in the assembly of matrix etc besides adding -pc_type hypre -pc_hypre_type boomeramg ?</div>
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<div>2. Can it work in a sequential code?</div>
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<div>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?</div>
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<div>Thank you.<br><br> </div>
<div><span class="gmail_quote">On 2/12/07, <b class="gmail_sendername">Barry Smith</b> <<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><br>hypre/boomeramg may be the way to go, especially for the Poisson<br>problem. -pc_type hypre -pc_hypre_type boomeramg (-help for lots of
<br>tuning options.).<br><br> Barry<br><br><br>On Sun, 11 Feb 2007, Ben Tay wrote:<br><br>> Well,<br>><br>> I am simulating unsteady flow past a moving airfoil at Re~10^4. I'm using<br>> fractional step FVM, which means that I need to solve a momentum and poisson
<br>> equation.<br>><br>> To reach a periodic state takes quite a few hours and so I'm trying to find<br>> ways to speed up the process. I thought parallelizing the code would help<br>> but it seems like it's not the case.
<br>><br>> I'm now trying out different types of solver/preconditioner available on<br>> PETSc to assess their performance. Is there other external solvers, which<br>> PETSc interfaces, which are recommended? I'm thinking of using multigrid to
<br>> solve the poisson eqn... wonder if hypre/BoomerAMG etc would help...<br>><br>><br>> On 2/11/07, Lisandro Dalcin <<a href="mailto:dalcinl@gmail.com">dalcinl@gmail.com</a>> wrote:<br>> ><br>> > On 2/10/07, Ben Tay <
<a href="mailto:zonexo@gmail.com">zonexo@gmail.com</a>> wrote:<br>> > > In other words, for my CFD code, it is not possible to parallelize it<br>> > > effectively because the problem is too small?<br>
> > ><br>> > > Is these true for all parallel solver, or just PETSc? I was hoping to<br>> > reduce<br>> > > the runtime since mine is an unsteady problem which requires many steps<br>> > to
<br>> > > reach a periodic state and it takes many hours to reach it.<br>> ><br>> > Can you describe your specific application and how are you solving it?<br>> > As Barry said, your need-for-speed is not likely to be solved by
<br>> > running in parallel.<br>> ><br>> ><br>> > --<br>> > Lisandro Dalcín<br>> > ---------------<br>> > Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)<br>
> > Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)<br>> > Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)<br>> > PTLC - Güemes 3450, (3000) Santa Fe, Argentina
<br>> > Tel/Fax: +54-(0)342-451.1594<br>> ><br>> ><br>> </blockquote></div><br>