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How to know the sign of the velocity ?

Posted Jun 30, 2012, 9:29 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.3 4 Replies

Osameh Ghazian
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Hi,
I need to know the sign of the velocity in my model , It seems that there is no option in COMSOL. I have tired different probes but all of them give you the magnitude of the velocity. I need to know when the velocity change its direction so I need to know the sign.
Best
4 Replies Last Post Jul 2, 2012, 1:40 a.m. EDT
Mohtadin Hashemi
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Posted: 1 decade ago Jun 30, 2012, 10:41 a.m. EDT
Hi,

Have you tried streamlines? Or do you want more information than that?

regards,
Hi, Have you tried streamlines? Or do you want more information than that? regards,
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Jul 1, 2012, 1:03 p.m. EDT
You are probably requesting the velocity magnitude which cannot be negative. You should instead look at the components of the velocity vector.

Nagi Elabbasi
Veryst Engineering
You are probably requesting the velocity magnitude which cannot be negative. You should instead look at the components of the velocity vector. Nagi Elabbasi Veryst Engineering
Osameh Ghazian
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Posted: 1 decade ago Jul 1, 2012, 6:57 p.m. EDT
Hi Nagi,
I have also tried the components but they are all positives.
Hi Nagi, I have also tried the components but they are all positives.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jul 2, 2012, 1:40 a.m. EDT
Hi
well normally u,v,w are positive in the +x,y,z directions, but you should be able to pplot the gradients too, this can also give you info when the flow changes direction

--
Good luck
Ivar
Hi well normally u,v,w are positive in the +x,y,z directions, but you should be able to pplot the gradients too, this can also give you info when the flow changes direction -- Good luck Ivar

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