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" a negative cell volume error " when import into fluent |
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October 1, 2017, 16:50
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" a negative cell volume error " when import into fluent
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#1 |
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New Member
muhamad elberens
Join Date: Feb 2017
Posts: 10
Rep Power: 9  |
i am working on a 2d vawt ( structure and unstructured doamins ) simulation using mesh motion technique and pointwise for mesh generation.
however i am already double checked the orientation of the structured and made sure that unstructured domains are oriented to +z, i examine also the area ratio. still get a negative cell volume error in fluent Sent from my SM-N920C using CFD Online Forum mobile app |
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October 1, 2017, 16:55
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#2 |
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Member
Abhinand
Join Date: Jun 2016
Posts: 75
Rep Power: 9 |
Please attach PW file for a rough idea to get to know the real problem
The problem could be unnoticed empty domains or blocks, or could be orientation error between structured and unstructured meshes |
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October 1, 2017, 17:05
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#3 |
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New Member
muhamad elberens
Join Date: Feb 2017
Posts: 10
Rep Power: 9 |
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October 1, 2017, 20:50
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#4 | |
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New Member
muhamad elberens
Join Date: Feb 2017
Posts: 10
Rep Power: 9 |
Quote:
Sent from my SM-N920C using CFD Online Forum mobile app |
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October 2, 2017, 12:15
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#5 |
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Senior Member
David Garlisch
Join Date: Jan 2013
Location: Fidelity Pointwise, Cadence Design Systems (Fort Worth, Texas Office)
Posts: 307
Rep Power: 14 |
I exported the grid to a cas file using File, export, CAE... in Pointwise V18.0R4.
I was able to import the cas file into fluent V18 without any reported negative cell volumes. Are you setting the double precision option during fluent cas import? |
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October 2, 2017, 12:28
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#6 |
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New Member
muhamad elberens
Join Date: Feb 2017
Posts: 10
Rep Power: 9 |
I imported cas file into fluent V15, double percision without negative cell error but when i click calculate it is only calculate two iteration then it gives me negative cell volume error
- i am using S-A model - velocity inlet 5m/s - 0.0005 timestep Sent from my SM-N920C using CFD Online Forum mobile app |
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October 2, 2017, 13:02
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#7 |
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Senior Member
David Garlisch
Join Date: Jan 2013
Location: Fidelity Pointwise, Cadence Design Systems (Fort Worth, Texas Office)
Posts: 307
Rep Power: 14 |
One other thing that I noticed is that the two sliding interface connectors are sharing end nodes. Topologically, this makes the grid point at this location shared by both the rotating near field domain AND the stationary far field domain.
I suspect that as the solution is running, this grid point is getting rotated by the inner domain. Since this point is also used by the outer domain, the outer domain becomes distorted resulting in the negative cells. You see this in Pointwise by rotating the near field domains a few degrees. The far field domain will become distorted. One way to fix this:
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October 2, 2017, 15:53
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#8 |
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New Member
muhamad elberens
Join Date: Feb 2017
Posts: 10
Rep Power: 9 |
mr.david thanks so much for your support, that way is working well.
Sent from my SM-N920C using CFD Online Forum mobile app |
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