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Hi Paul,<br>
It helped a lot. But let me insist on the question of <span class="spellcheckCorrected" index="0">accuracy</span>. If the problem is well resolved (and spectrally accurate) then the divergence error could matter. No?<br>
I am interested to simulate turbulent flows so, this is the reason why I am concerning about this issue.<br>
Thanks again and have a nice weekend.<img alt="smiley" height="20" src="cid:2VoZUptDWw9Sqz8wSn4uZfA@webmail.tau.ac.il" title="smiley" width="20"><br>
Barak<br>
<br>
Quoting <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a>:</p>
<blockquote style="border-left:2px solid blue;margin-left:8px;padding-left:8px;" type="cite">
<p>Hi Barak,<br>
<br>
I have just a bit of time but will try to give you some quick answers to start.<br>
<br>
Interpolation is spectral.<br>
<br>
Decreasing div error simply sets the iteration tolerance tighter ---<br>
meaning that the _discrete_ system is solved to a tighter tolerance<br>
(i.e., closer to machine precision). However, it does not mean that<br>
the divergence is necessarily smaller, since there is also a discretization<br>
error associated with the fact that you are solving the discretized problem<br>
and not the continuous one. Discretization error can be reduced by<br>
increasing lx1 or the number of elements.<br>
<br>
If your problem is nondimensionalized in terms of convective timescales,<br>
I find div=1.e-6 is generally adequate (except, say, for certain<br>
stability problems, which tend to be very sensitive). If you are working<br>
in physical units, I would suggest set div=0 and tolrel = 0.01 ---- this<br>
will automatically choose tolerances for you. (It tends to be a bit more<br>
conservative than the 1.e-6 value that I suggest above.)<br>
<br>
There is a moving boundary example in the peristaltic flow example (/peris)<br>
At present, I don't have any falling body examples. Such a case is either<br>
easy or very hard, depending on the flow domain.<br>
<br>
hth,<br>
<br>
Paul<br>
<br>
<br>
----- Original Message -----<br>
From: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a><br>
To: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a><br>
Sent: Friday, December 13, 2013 3:44:49 AM<br>
Subject: Re: [Nek5000-users] Lagrangian particle tracking<br>
<br>
Hi Katherine,<br>
<br>
I reinstalled the new version (981) and indeed the code is running. I am<br>
going to check now the results.<br>
<br>
In previous messages I asked:<br>
1. Is the used interpolation spectral?<br>
2. When I decrease the desired divergence error, how does it increase<br>
the computation time?<br>
3. Are there examples for moving solid bodies or boundaries?<br>
<br>
Many thanks.<br>
Barak<br>
<br>
On 12/12/2013 10:14 PM, <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a> wrote:</p>
<blockquote style="border-left:2px solid blue;margin-left:8px;padding-left:8px;" type="cite">
<p>Hi Barak,<br>
<br>
I believe your error is a result of a compiler specific update. I have<br>
updated the Nek source code to hopefully address this issue. Please<br>
update your code and let me know if the problem is not resolved.<br>
<br>
Thanks<br>
Katherine<br>
<br>
<br>
On Thu, Dec 12, 2013 at 12:06 PM, <<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a><br>
<mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov>>">nek5000-users@lists.mcs.anl.gov>></a> wrote:<br>
<br>
Hei Paul,<br>
I tried your example and I get just at the beginning an error. See<br>
the attached file.<br>
<br>
Thanks,<br>
Barak<br>
<br>
On 12/11/2013 02:51 AM, <a href="mailto:nek5000-users@lists.mcs.anl">nek5000-users@lists.mcs.anl</a>.__gov<br>
<mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov>">nek5000-users@lists.mcs.anl.gov></a> wrote:<br>
<br>
<br>
Hi,<br>
<br>
I've added a Lagrangian particle tracking example ---<br>
<br>
examples/hemi<br>
<br>
look at hemi.usr.<br>
<br>
It produces a sequence of files with particle positions and<br>
a matlab script is provided for viewing. As soon as I have<br>
a chance I'll also develop a script for visit.<br>
<br>
Paul<br>
<br>
<br>
----- Original Message -----<br>
From: <a href="mailto:nek5000-users@lists.mcs.anl">nek5000-users@lists.mcs.anl</a>.__gov<br>
<mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov>">nek5000-users@lists.mcs.anl.gov></a><br>
To: <a href="mailto:nek5000-users@lists.mcs.anl">nek5000-users@lists.mcs.anl</a>.__gov<br>
<mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov>">nek5000-users@lists.mcs.anl.gov></a><br>
Sent: Tuesday, December 10, 2013 4:25:19 PM<br>
Subject: Re: [Nek5000-users] Lagrangian particle tracking<br>
<br>
On 12/10/2013 03:27 PM, <a href="mailto:nek5000-users@lists.mcs.anl">nek5000-users@lists.mcs.anl</a>.__gov<br>
<mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov>">nek5000-users@lists.mcs.anl.gov></a> wrote:<br>
<br>
Le 10/12/2013 13:00, <a href="mailto:nek5000-users@lists.mcs.anl">nek5000-users@lists.mcs.anl</a>.__gov<br>
<mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov>">nek5000-users@lists.mcs.anl.gov></a> a écrit<br>
<br>
<br>
<br>
Hello,<br>
<br>
What do you want to known about Lagrangian Particle<br>
Tracking ?<br>
<br>
<br>
<br>
Hi Anne,<br>
I would like to perform some Lagrangian particle simulation to to<br>
compute the component of the velocity field or vorticity at the<br>
particle. Do you have example for such computation as described<br>
in the<br>
webpage:<br>
<a href="http://nek5000.mcs.anl.gov/__index.php/Data_processing___example" target="_blank">http://nek5000.mcs.anl.gov/__index.php/Data_processing___example</a><br>
<<a href="http://nek5000.mcs.anl.gov/index.php/Data_processing_example" target="_blank">http://nek5000.mcs.anl.gov/index.php/Data_processing_example</a>><br>
Thanks,<br>
<br>
Barak<br>
<br>
<br>
Anne Tanière<br>
<br>
<br>
Hi<br>
I am interested to know if there is an example for the<br>
Lagrangian<br>
particle tracking<br>
as described in<br>
<a href="http://nek5000.mcs.anl.gov/__index.php/Data_processing___example" target="_blank">http://nek5000.mcs.anl.gov/__index.php/Data_processing___example</a><br>
<<a href="http://nek5000.mcs.anl.gov/index.php/Data_processing_example" target="_blank">http://nek5000.mcs.anl.gov/index.php/Data_processing_example</a>><br>
.<br>
<br>
Thanks,<br>
Barak Galanti<br>
<br>
<br>
<br>
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--<br>
Pr. Anne Tanière, Lorraine University<br>
Nouvel email:anne.taniere@univ-__lorraine.fr<br>
<mailto:<a href="mailto:email%3Aanne.taniere@univ-lorraine.fr>">email%3Aanne.taniere@univ-lorraine.fr></a><br>
Responsable des stages 5A, MFE ESSTIN<br>
tel : 03.83.68.50.83<br>
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