There is a bug in the computed Q criterion where the vorticity part was missing a factor of 0.5. I would suggest you compute Q criterion from the output of the gradient filter. For the gradient of unstructured data set filter, if the compute vorticity option is selected its result gets put in the result array name instead of the velocity gradient. There has been much confusion on this and it will get fixed in ParaView 4.0. <br>
<br>The stream tracer filter doesn't rely on grid connectivity to traverse the mesh. You may want to look at the seed source that you're using or maybe some other parameters of the stream tracer filter.<br><br><div class="gmail_quote">
On Tue, Jul 24, 2012 at 6:54 PM, Mei Chen <span dir="ltr"><<a href="mailto:mei.chen.web@gmail.com" target="_blank">mei.chen.web@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,<div><br></div><div>I have paraview 3.14 with 64-bit Win7. I have an ensight file with about 5 million points. I used GradientOfUnstructuredDataSet to calculate the gradient, and use the gradient to calculate the Q-value for vortex detection (the Q-criterion). </div>
<div><br></div><div>(1) The selected points does not support any evidence of vortex. Does anyone know how the GradientOfUnstructuredDataSet filter work?</div><div><br></div><div>(2) <span style="font-family:Arial">I also compute the vorticity (this option is under
GradientOfUnstructuredDataSet filter) but I did not find any resulted variable in the list.
I was thinking using it to do vortex detection. Can anyone tell me where to find this variable?</span></div>
<div><br></div><div>(3) <span style="font-family:Arial">The result of stream trace filter is noting (cell/point number is 0) as I think it is due to the lack of gird connectivity. I tried </span><span style="font-family:Arial">GridConnecivity filter to make the connection but I failed. </span><span style="font-family:Arial">The vtkErrorMessage: “Missing pedigree
node array.”, “This filter cannot handle sub-datasets of type:
vtkUnstructuredGrid. Skipping block.”, and “ExecuteProcess: Unknown input
ScalarType.” Can anyone tell me what does the pedigree node mean and how can I get streamline with the unstructured grid?</span></div><div><span style="font-family:Arial"><br></span></div><div><span style="font-family:Arial">Tons of thank!</span></div>
<div><span style="font-family:Arial"><br></span></div><div><span style="font-family:Arial">Best,</span></div><div><span style="font-family:Arial">Mei Chen</span></div>
<div><br></div>
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