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<pre wrap=""><span class="moz-txt-star">Amitvikram,
Hi... I'm doing very high Re on some wind turbine wake flows, and yes, I have resolution problems also. I had to drastically reduce my time step/CFL to prevent blowup. Then, my results showed much more "clutter" (poor resolution), and "exposed" the grid element outlines in isosurface plots; I assume from gradients near the element boundaries...
Increasing DOF and reducing grid spacing did help resolve the problem; vortices and other flow structures became much more defined. However, the "exposed grid" is still there, and I have not reduced the grid spacing enough yet to see these artifacts completely removed...
See Ya,
Murph O'Dea
</span></pre>
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<br>
<div class="moz-cite-prefix">On 3/16/2016 1:00 PM,
<a class="moz-txt-link-abbreviated" href="mailto:nek5000-users-request@lists.mcs.anl.gov">nek5000-users-request@lists.mcs.anl.gov</a> wrote:<br>
</div>
<blockquote
cite="mid:mailman.42.1458147612.31749.nek5000-users@lists.mcs.anl.gov"
type="cite">
<pre wrap="">can you send me a picture of that, perhaps off-list? (<a class="moz-txt-link-abbreviated" href="mailto:pschlatt@mech.kth.se">pschlatt@mech.kth.se</a>).
Thanks,
Philipp
On 2016-03-16 16:04, <a class="moz-txt-link-abbreviated" href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a> wrote:
Hi Philipp,
My Geometry is a 2D C Grid of a NACA airfoil. And yes, wiggles leading
to a blow up are exactly how I would describe my problems.
Sincerely,
On Wed, Mar 16, 2016, 7:47 AM <<a class="moz-txt-link-abbreviated" href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a>
<a class="moz-txt-link-rfc2396E" href="mailto:nek5000-users@lists.mcs.anl.gov"><mailto:nek5000-users@lists.mcs.anl.gov></a>> wrote:
Hi,
what type of problems do you have? Are you looking at a 3D geometry? Do
you get wiggles, which then lead to a blow up?
Best,
Philipp
On 2016-03-15 20:26, <a class="moz-txt-link-abbreviated" href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a>
<a class="moz-txt-link-rfc2396E" href="mailto:nek5000-users@lists.mcs.anl.gov"><mailto:nek5000-users@lists.mcs.anl.gov></a> wrote:
> Hello all,
>
> I was wondering if anyone on the mailing list has experience with
> simulating high Re flows of the order 10<sup class="moz-txt-sup"><span style="display:inline-block;width:0;height:0;overflow:hidden">^</span>5</sup>. I'm studying flow
> instabilities over airfoils and have been struggling to obtain a
stable
> simulation for these high Re flows.
>
> Its worthwhile to note that I have simulated low Re flows using
> identical geometries. Making the mesh finer or increasing the
order of
> the method does not seem to be doing the trick. The simulations
usually
> diverge after something like 5 seconds of flow time.
>
> If there are any specific conditions/settings that I should be
looking
> at, I'd really appreciate the information.
>
> Thanks,
> --
>
> <b class="moz-txt-star"><span class="moz-txt-tag">*</span>Amitvikram Dutta<span class="moz-txt-tag">*</span></b>
>
> *MASc Candidate**
> *
>
> *Graduate Research Assistant *
>
> <b class="moz-txt-star"><span class="moz-txt-tag">*</span>Okanagan CFD Laboratory<span class="moz-txt-tag">*</span></b>
>
> *University of British Columbia | Okanagan Campus***
>
>
>
> _______________________________________________
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--
<b class="moz-txt-star"><span class="moz-txt-tag">*</span>Amitvikram Dutta<span class="moz-txt-tag">*</span></b>
*MASc Candidate**
*
*Graduate Research Assistant *
<b class="moz-txt-star"><span class="moz-txt-tag">*</span>Okanagan CFD Laboratory<span class="moz-txt-tag">*</span></b>
*University of British Columbia | Okanagan Campus***
Re: Nek5000 simulations of High Re flows ~ 10<sup class="moz-txt-sup"><span style="display:inline-block;width:0;height:0;overflow:hidden">^</span>5</sup></pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Murphy Leo O'Dea
PhD Student
Oakland University
<a class="moz-txt-link-abbreviated" href="mailto:mlodea@oakland.edu">mlodea@oakland.edu</a></pre>
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