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<div class="moz-cite-prefix">On 27/3/2014 12:14 AM, Matthew Knepley
wrote:<br>
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cite="mid:CAMYG4Gkcy20mZ6NWBZ2n_R_RtcEZaUXBW-2jZqGknnTeFaw4BQ@mail.gmail.com"
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<div class="gmail_quote">On Wed, Mar 26, 2014 at 10:42 AM, TAY
wee-beng <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:zonexo@gmail.com" target="_blank">zonexo@gmail.com</a>></span>
wrote:<br>
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<div>On 26/3/2014 11:22 PM, Matthew Knepley wrote:<br>
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<div class="gmail_quote">On Wed, Mar 26, 2014 at
9:59 AM, TAY wee-beng <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:zonexo@gmail.com"
target="_blank">zonexo@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0
0 0 .8ex;border-left:1px #ccc
solid;padding-left:1ex">Hi,<br>
<br>
I am running a CFD solver. The Poisson eqn was
originally solved using HYPRE's geometric
multigrid.<br>
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<div>Is this on a structured grid?</div>
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<br>
Yes.<br>
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<div>Then you can replicate the Hypre structured MG with the
PCMG, and it can be lighter memory than GAMG. You</div>
<div>will need to code the problem in the style of SNES ex5,
which is a Poisson for which geometric MG works from</div>
<div>the command line.</div>
<div><br>
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<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
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Hi Matt,<br>
<br>
First of all, is there an easier way out? Is it Boomeramg or GMRES
which has a large memory requirement? Will changing e.g. GMRES to
FGMRES or other ksp solvers solve the problem?<br>
<br>
Also, I switched from geometric multigrid (GMG) to Boomeramg because
the latter is faster. If I use PCMG, am I going back to the GMG
path, which was slower?<br>
<br>
Thanks!<br>
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cite="mid:CAMYG4Gkcy20mZ6NWBZ2n_R_RtcEZaUXBW-2jZqGknnTeFaw4BQ@mail.gmail.com"
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<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0
0 0 .8ex;border-left:1px #ccc
solid;padding-left:1ex"> Recently, I tested it
with Boomeramg as the preconditioner and GMRES
as the ksp solver. There's a 20% increase in
speed.<br>
<br>
However, when I increased the grid resolution,
I got the out of memory error. Changing the
solver back to HYPRE solved the problem.<br>
<br>
So does GMRES + Boomeramg used more memory
than other solvers? Are there alternatives?<br>
<br>
Thank you.<span class="HOEnZb"><font
color="#888888"><span><font
color="#888888"><br>
<br>
-- <br>
Yours sincerely,<br>
<br>
TAY wee-beng<br>
<br>
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<span class="HOEnZb"><font color="#888888"> </font></span></div>
<span class="HOEnZb"><font color="#888888"> <br>
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<div><br>
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-- <br>
What most experimenters take for granted
before they begin their experiments is
infinitely more interesting than any results
to which their experiments lead.<br>
-- Norbert Wiener </font></span></div>
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<div><br>
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-- <br>
What most experimenters take for granted before they begin
their experiments is infinitely more interesting than any
results to which their experiments lead.<br>
-- Norbert Wiener
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