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Paul,
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<div class="">is there a paper/report we can have access to that goes in the details of the implementation, please? Also, are the typical values based on your personal experience?</div>
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<div class="">Thanks,</div>
<div class="">Marco<br class="">
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<div class="">On Jun 27, 2016, at 8:55 AM, <a href="mailto:nek5000-users@lists.mcs.anl.gov" class="">
nek5000-users@lists.mcs.anl.gov</a> wrote:</div>
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Hi Andrew,
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<div class="">The projection routines are currently being overhauled, but the general strategy is:</div>
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<div class=""> Number of projections controlled by p93 and mxprev in SIZE. </div>
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<div class=""> p94 > 0: start projecting velocity/temp after step p94</div>
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<div class=""> p95 > 0: start projecting pressure after step 95</div>
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<div class="">I typically set p94 and p95 to 5</div>
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<div class="">I set mxprev and p93 to 20, but sometimes to a higher value.</div>
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<div class="">I used to occasionally to to much higher than 20 (say, 80), but in a recent</div>
<div class="">rewrite and effort to make projection more robust I slowed the projection</div>
<div class="">step down with too much work, so another rewrite is due soon.</div>
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<div class="">Paul</div>
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<div class="">PS - note that certain combinations of run parameters don't support</div>
<div class="">projection or potentially blow up. Set p94=0 in this case and retry.</div>
<div class="">There was a bug that was fixed about 6 weeks back---it may have cured</div>
<div class="">some of the cases that users were running into.</div>
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<div id="divRpF765626" style="direction: ltr;" class=""><font face="Tahoma" size="2" class=""><b class="">From:</b><span class="Apple-converted-space"> </span><a href="mailto:nek5000-users-bounces@lists.mcs.anl.gov" class="">nek5000-users-bounces@lists.mcs.anl.gov</a>
[<a href="mailto:nek5000-users-bounces@lists.mcs.anl.gov" class="">nek5000-users-bounces@lists.mcs.anl.gov</a>] on behalf of
<a href="mailto:nek5000-users@lists.mcs.anl.gov" class="">nek5000-users@lists.mcs.anl.gov</a> [<a href="mailto:nek5000-users@lists.mcs.anl.gov" class="">nek5000-users@lists.mcs.anl.gov</a>]<br class="">
<b class="">Sent:</b><span class="Apple-converted-space"> </span>Monday, June 27, 2016 3:17 AM<br class="">
<b class="">To:</b><span class="Apple-converted-space"> </span><a href="mailto:nek5000-users@lists.mcs.anl.gov" class="">nek5000-users@lists.mcs.anl.gov</a><br class="">
<b class="">Subject:</b><span class="Apple-converted-space"> </span>[Nek5000-users] Projection technique's parameters<br class="">
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<div dir="ltr" class=""><span lang="en" class=""><span class="">Hi Neks,<br class="">
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</span></span>My question is about the parameters which manage the projection method in the NEK5000: p93, p94 and p95. How can the correct values be selected for these parameters to obtain the better performance depending on the nature of simulation: laminar
/ turbulent, convection / diffusion, time step?<br class="">
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<span lang="en" class="">Thank you for any suggestion,<span class="Apple-converted-space"> </span><br class="">
</span><span lang="en" class="">Andrew</span><br class="">
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