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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 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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