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June 11, 2010, 14:04 |
Is this correct? (Rotating domain)
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#1 |
Member
Paulo Alexandre Costa Rocha
Join Date: Mar 2009
Posts: 71
Rep Power: 17 |
Dear all,
I simulated a rotating cube with three domains (two static and one rotating). This is the result of the streamlines. For me they seem very strange (I thought they would deflect only near the cube). I apreciate any comments. Best Regards, Paulo Rocha |
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June 11, 2010, 16:08 |
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#2 |
Senior Member
Attesz
Join Date: Mar 2009
Location: Munich
Posts: 368
Rep Power: 17 |
Hi,
your fluid has a very low velocity. What is your rotating speed? Don't forget, that you rotate not only the cube, but the whole flow field in the rotating domain. |
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June 13, 2010, 12:00 |
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#3 |
Member
Paulo Alexandre Costa Rocha
Join Date: Mar 2009
Posts: 71
Rep Power: 17 |
Thanks for the comment. In fact, I see that the whole domain is rotating. This is what was not desired. I would like to move the mesh (only), like this:
http://www.youtube.com/watch?v=1xZ3W3ST1Lo The fluid doesn't rotate when it enters in the rotating zone. Is this possible in CFX? Thanks in advance. Paulo Rocha |
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June 13, 2010, 12:08 |
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#4 |
Senior Member
Attesz
Join Date: Mar 2009
Location: Munich
Posts: 368
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Yes, you should use moving mesh, which can be accurate then the rotating frames. But maybe smarter users will help you, i'm not experienced in it.
Anyway, your rotating domain is very large. You should define the rotating region only near that cube, but in your case, the moving mesh can be more suitable. |
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June 14, 2010, 10:42 |
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#5 |
Member
Paulo Alexandre Costa Rocha
Join Date: Mar 2009
Posts: 71
Rep Power: 17 |
Thank you very much Attila,
I will wait for better insights. Best Regards, Paulo Rocha |
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June 14, 2010, 19:47 |
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#6 | |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,850
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Quote:
Your "problem" is that you are looking at velocity in the local frame of reference. Make the variable "velocity in stationary frame" and the streamlines will be as you expect. |
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June 15, 2010, 04:03 |
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#7 | |
Senior Member
Attesz
Join Date: Mar 2009
Location: Munich
Posts: 368
Rep Power: 17 |
Quote:
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June 15, 2010, 07:59 |
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#8 | |||
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,850
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Quote:
Quote:
Quote:
No, there is no cases where moving mesh is a better approach than a simple rotating frame of reference if the body just rotates. |
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June 15, 2010, 08:02 |
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#9 |
Senior Member
Attesz
Join Date: Mar 2009
Location: Munich
Posts: 368
Rep Power: 17 |
Ok, thanks Glenn.
Attesz |
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June 15, 2010, 10:59 |
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#10 |
Member
Paulo Alexandre Costa Rocha
Join Date: Mar 2009
Posts: 71
Rep Power: 17 |
Dear Attila and Glenn,
I am really happy with your help. I will try every tip tomorrow and post the results. Best Regards, Paulo Rocha PS: It is only a test case. My intention is to put a wind turbine in the place of the cube. |
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June 17, 2010, 14:19 |
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#11 |
Member
Paulo Alexandre Costa Rocha
Join Date: Mar 2009
Posts: 71
Rep Power: 17 |
Here is the result. I think it is working fine now.
Thank you all. Best Regards, Paulo Rocha |
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