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<blockquote type="cite">Indeed, my smaller mesh had linear
triangles. And changing that to quadratic triangles gives the same
behavior (attachment).</blockquote>
I experimented a bit with the data you send and there does seem to
be a problem with the quadratic triangles. However, I found that
with linear triangles the result is correct.<br>
<br>
One thing I noticed about your test data is this velocity field is a
<a href="http://en.wikipedia.org/wiki/Vortex#Vorticity_profiles">special
case</a> , where v increases proportional with distance to vortex
center. For this case vorticity is a constant. This means in PV
you'll just see a single color in the plot, so it looks the same for
both linear(good result) and quadratic triangles(bad result). This
is something to be aware of!<br>
<br>
<br>
<img src="cid:part2.04000201.00050402@gmail.com" alt=""><br>
<br>
<br>
<blockquote type="cite">The reason why I wanna use the vorticity
function is the following: eddies appear all over the domain and
using lines with the streamtracer filter gives regions with either
no streamlines or regions that are very much crowded by
streamlines. Therefore, having a vorticity field would be a
suitable approach to have a nice and clean visualization of the
flow field.</blockquote>
In addition to visualizing vorticity the LIC visualization technique
may be useful for you as well.<br>
<a class="moz-txt-link-freetext" href="http://www.paraview.org/Wiki/ParaView/Line_Integral_Convolution">http://www.paraview.org/Wiki/ParaView/Line_Integral_Convolution</a><br>
<br>
Burlen<br>
<br>
<div class="moz-cite-prefix">On 05/21/2014 02:32 PM, Andreas
Hessenthaler wrote:<br>
</div>
<blockquote cite="mid:20140521213208.7D07243475@postfix01.mail.de"
type="cite">Indeed, my smaller mesh had linear triangles. And
changing that to quadratic triangles gives the same behavior
(attachment).<br>
<p>What is the best way to circumvent this?</p>
<p>The reason why I wanna use the vorticity function is the
following: eddies appear all over the domain and using lines
with the streamtracer filter gives regions with either no
streamlines or regions that are very much crowded by
streamlines. Therefore, having a vorticity field would be a
suitable approach to have a nice and clean visualization of the
flow field.</p>
<p>Cheers</p>
<p><br>
Am 21-May-2014 17:00:55 +0200 schrieb <a class="moz-txt-link-abbreviated" href="mailto:andy.bauer@kitware.com">andy.bauer@kitware.com</a>:</p>
<blockquote style="margin-left: 0; padding-left: 5px; border-left:
2px solid navy;">
<div dir="ltr">It looks like these are quadratic triangles. I'm
not sure that the compute derivatives filter works with that
type of cell. Did your smaller grid also have quadratic cell
types?</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Wed, May 21, 2014 at 9:51 AM,
Andreas Hessenthaler wrote:<br>
<blockquote class="gmail_quote" style="margin: 0 0 0 .8ex;
border-left: 1px #ccc solid; padding-left: 1ex;">Hi Andy,<br>
<p>thanks for your quick reply. Please find the *.vtu file
attached.</p>
<p>Cheers<br>
Andreas</p>
<p> </p>
<p><br>
Am 21-May-2014 15:24:30 +0200 schrieb <a
moz-do-not-send="true"
href="mailto:andy.bauer@kitware.com" target="_blank">andy.bauer@kitware.com</a>:</p>
<blockquote style="margin-left: 0; padding-left: 5px;
border-left: 2px solid #000080;">
<div dir="ltr">Can you share your data set? It will be
difficult to diagnose without that.</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Wed, May 21, 2014 at 9:06
AM, Andreas Hessenthaler wrote:<br>
<blockquote class="gmail_quote" style="margin: 0 0 0
.8ex; border-left: 1px #ccc solid; padding-left:
1ex;">Hi there,<br>
<p>I have the following problem:</p>
<p>When I calculate the vorticity through Filters
> Compute Derivatives > Vorticity for a
simple example (driven cavity in 2D) with only
few elements on an unstructured grid I get the
correct values.</p>
<p>Though, when I do the same for a bigger domain,
i.e. more elements (~80 000 nodes), I only get
zero vorticity values.</p>
<p>The grids and values are all read in from *.vtu
files, with the exact same format, meshes are
triangluar 2D (z-components set to 0.0).</p>
<p>I can reproduce the behavior on different
versions of ParaView: 3.14.1 & 4.1.0 as well
as different operating systems: Windows 7 &
Ubuntu 14.04.</p>
<p>If I calculate the gradient of the velocity
field, all values are calculated as zero as
well.</p>
<p>Thanks in advance!</p>
<p>Cheers<span style="color: #888888;"><br>
Andreas</span></p>
<br>
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