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<p>Hello everyone,</p>
<p><br>
</p>
<p>Sorry for the delay, I was exploring all the possibilities that
you have provided to me! I believe that the problem was solved.<br>
</p>
<p>Here is what I have done : <br>
</p>
<p><br>
</p>
<p>I have increased lx1, I have computed the components of the
vorticity field using wgradm1. Then when I compute gradient of
vorticity for every iteration, I diffuse it over 5 time steps
(with low values of dt) and this removes the problem at the
interface of the elements!</p>
<p><br>
</p>
<p>Thank you for your help,</p>
<p><br>
</p>
<p>Best wishes,</p>
<p><br>
</p>
<p>Arnold<br>
</p>
<p><br>
</p>
<br>
<div class="moz-cite-prefix">Le 06/03/2017 à 07:38, Arnold Wakim a
écrit :<br>
</div>
<blockquote cite="mid:cc5f1ae0-7219-77fb-f81d-26279406cada@onera.fr"
type="cite">
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<p>Good Morning,</p>
<p><br>
</p>
<p>Sorry for taking so long to answer. First I wanted to say that
I really appreciate all of your help! <br>
</p>
<p>I am currently trying all these methods : <br>
</p>
<p>- as suggested by Paul Fischer, increasing LX1 and low pass
filtering.<br>
</p>
<p>- and smoothing the derivatives. I will keep you posted on the
results.<br>
</p>
<p><br>
</p>
<p>What I am trying to do is studying optimal perturbations using
a DIRECT-ADJOINT approach so as to optimize quantities. <br>
However, when I am writing the equations, I have no choice but
taking the spatial derivatives of vorticity. <br>
</p>
<p>Computing the derivatives is made for every DIRECT Numerical
Simulation of the perturbations. Then I call the ADJOINT solver
of Nek5000</p>
<p>In order to converge towards optimum this may take several
iterations let's say N ( roughly N=10 however since the
gradients are not well resolved then I cannot tell whether I'm
converged or not). The point is that I am computing vorticity,
then computing the gradients of the same initial field, and
this, N times. This leads to the problem I am facing. <br>
</p>
<p>Hope that helps understanding the issue. If you have more
questions, please do not hesitate to ask.</p>
<p><br>
</p>
<p>Best wishes,</p>
<p><br>
</p>
<p>Arnold<br>
</p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">Le 03/03/2017 à 21:33, <a
moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a>
a écrit :<br>
</div>
<blockquote
cite="mid:mailman.1580.1488574096.2967.nek5000-users@lists.mcs.anl.gov"
type="cite">call col2(dTdx,bm1,n) ! collocate
with the mass matrix<br>
call dssum(dTdx,nx1,ny1,nz1) ! smooth<br>
call col2(dTdx,bintm1,n) ! collocate with the
inverse mass matrix</blockquote>
<br>
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Doctorant,<br>
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Tél: +33 1 46 23 51 83</font></font></font></p>
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align="left" border="0" height="35" width="70"><strong><font
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Wakim</font></font></font></strong><font color="#0668b3"><font
face="Arial, Helvetica, sans-serif"><font style="font-size:
9pt" size="2"><br>
Doctorant,<br>
Département
d´</font></font></font><font color="#0668b3"><font
face="Arial, Helvetica, sans-serif"><font style="font-size:
9pt" size="2">A</font></font></font><font color="#0668b3"><font
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9pt" size="2">xpérimentale<br>
Tél:
+33 1 46 23 51 83</font></font></font></p>
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