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Streamline Plot

Posted Jul 26, 2010, 2:54 a.m. EDT 6 Replies

Markus Berger
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Hi everybody,
pleas help with an postprocessing issue:
I set up a conjugate heat transfer model, the model solves successfully.
If I want to view the 3D-velocity field as a stremline plot I run into trouble:
A start point controlled plot with 20 startpoints gives me two visible streamlines, 200 startpoints give
a few more, but there are always 90% missing.
If I switch to any other plot mode, e.g. "uniform density" I get an error message from streamplot.
I have found something similar as a bug report, but this was claimed to be fixed with the first 4.0 hotfix.
I am using 4.0a though, also an ever later release.
Any hints here?

Thanks!
6 Replies Last Post Sep 22, 2010, 1:42 a.m. EDT
Zoran Vidakovic, COMSOL COMSOL Employee

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Posted: 1 decade ago Jul 28, 2010, 3:46 a.m. EDT
Hi Markus

Can you post some screenshots or your model here in order to see the problem?
If the file size is too big (>5MB) please create a new simple model from scratch and try to reproduce this issue and send it to me.

Best,
Zoran
Hi Markus Can you post some screenshots or your model here in order to see the problem? If the file size is too big (>5MB) please create a new simple model from scratch and try to reproduce this issue and send it to me. Best, Zoran
Markus Berger
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Posted: 1 decade ago Jul 28, 2010, 7:52 a.m. EDT
Hi Zoran,

thanks for your reply.
I have attached a screenshot of the situation. The fluid volume (air) fills all of the enclosure
and this is what I get for 20 startpoint-controlled streamlines.
Best Markus
Hi Zoran, thanks for your reply. I have attached a screenshot of the situation. The fluid volume (air) fills all of the enclosure and this is what I get for 20 startpoint-controlled streamlines. Best Markus

Attachments:

Zoran Vidakovic, COMSOL COMSOL Employee

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Posted: 1 decade ago Jul 28, 2010, 8:15 a.m. EDT
Interesting.

What are your settings of streamline?

Try another positioning method "Uniform density" and chose an appropriate "Separating distance" (see attached figure).

Zoran
Interesting. What are your settings of streamline? Try another positioning method "Uniform density" and chose an appropriate "Separating distance" (see attached figure). Zoran

Attachments:

Markus Berger
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Posted: 1 decade ago Jul 28, 2010, 9:00 a.m. EDT
Hi,

thanks again for your quick reply.
I have tried the "seperating distance" and it gives somewhat less awkward results but still looks strange.
If I try to start the streamlines from a useful location (e.g. some inlet boundary) using coordinate
ranges, neither the number of resulting lines nor the starting coords seem to be correct. (See pics)
BTW: This is already 4.0.0.933

Best
Markus
Hi, thanks again for your quick reply. I have tried the "seperating distance" and it gives somewhat less awkward results but still looks strange. If I try to start the streamlines from a useful location (e.g. some inlet boundary) using coordinate ranges, neither the number of resulting lines nor the starting coords seem to be correct. (See pics) BTW: This is already 4.0.0.933 Best Markus
Michael Drews
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Posted: 1 decade ago Sep 22, 2010, 1:42 a.m. EDT
I ran into a similar problem when I was modeling a fluids problems as well. I had what looked like a reasonably good velocity magnitude sectional plots, but then when I tried the streamline a got some segments and only a few lines going through, even though I used 200 startpoints. I refined the mesh and got much better results. I think the velocity field was not accurately defined throughout the volume using my original mesh, so the streamlines were not truly continuous. So maybe try to crank up your mesh density and see how it goes.

Best,
Mike
I ran into a similar problem when I was modeling a fluids problems as well. I had what looked like a reasonably good velocity magnitude sectional plots, but then when I tried the streamline a got some segments and only a few lines going through, even though I used 200 startpoints. I refined the mesh and got much better results. I think the velocity field was not accurately defined throughout the volume using my original mesh, so the streamlines were not truly continuous. So maybe try to crank up your mesh density and see how it goes. Best, Mike
Michael Drews
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Posted: 1 decade ago Sep 22, 2010, 1:42 a.m. EDT
I ran into a similar problem when I was modeling a fluids problems as well. I had what looked like a reasonably good velocity magnitude sectional plots, but then when I tried the streamline a got some segments and only a few lines going through, even though I used 200 startpoints. I refined the mesh and got much better results. I think the velocity field was not accurately defined throughout the volume using my original mesh, so the streamlines were not truly continuous. So maybe try to crank up your mesh density and see how it goes.

Best,
Mike
I ran into a similar problem when I was modeling a fluids problems as well. I had what looked like a reasonably good velocity magnitude sectional plots, but then when I tried the streamline a got some segments and only a few lines going through, even though I used 200 startpoints. I refined the mesh and got much better results. I think the velocity field was not accurately defined throughout the volume using my original mesh, so the streamlines were not truly continuous. So maybe try to crank up your mesh density and see how it goes. Best, Mike

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