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pressure field problem in simulation of Couette flow |
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July 13, 2018, 04:03 |
pressure field problem in simulation of Couette flow
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#1 |
New Member
VU Tuan-Long
Join Date: Jan 2018
Posts: 6
Rep Power: 8 |
Hi everyone,
I'm trying to simulate Coutte flow. First I created a rectangular surface of 20x1 cm, then I set the boundary condition for the front and back lines as periodic, lower line as no-slip stationary wall, and upper line as moving wall at 0.1 m/s. The used fluid was liquid water. I don't know why I got the result for the pressure field like below, which, theoretically, is supposed to be constant. couette pressure.PNG I'm new to CFD, so please kindly help. Thanks a lot! |
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July 13, 2018, 04:32 |
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#2 |
Member
Leonardo
Join Date: Nov 2017
Posts: 37
Rep Power: 8 |
Try pressure inlet and outlet = 0 Pa. Also, what is your mesh resolution?
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July 13, 2018, 11:37 |
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#3 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,748
Rep Power: 66 |
Would be nice to see the colorbar scale to see if it is even a significant change in pressure.
And does the velocity make sense and look like the theoretical solution? If no, then there's no way the pressure contour will make sense. Remember pressure is whatever it needs to be to satisfy the constraints on the problem. So first check a more relevant parameter like velocity. |
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July 15, 2018, 00:41 |
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#4 |
New Member
VU Tuan-Long
Join Date: Jan 2018
Posts: 6
Rep Power: 8 |
Thanks Leonardo for your suggestion. But this is exactly one of ways I tried in the first place and I got a wierd flow result. My mesh is 100x10. Is this a good mesh for such a flow?
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July 15, 2018, 00:46 |
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#5 | |
New Member
VU Tuan-Long
Join Date: Jan 2018
Posts: 6
Rep Power: 8 |
Quote:
The velocity is like the theoretical solution. The pressure difference is 1.4 Pa. How can I tell whether it is significant or not? couette pressure.PNG |
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July 15, 2018, 02:51 |
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#6 |
Member
Leonardo
Join Date: Nov 2017
Posts: 37
Rep Power: 8 |
As I can see in the colorbar you have a range from -8e-10 to 6e-10 Pa. That can be considered as a zero constant pressure. So those fluctuations in the field could be numerical errors then!
Just deactivate the automatic data range and define a wider range. The field should become constant then. |
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July 16, 2018, 00:14 |
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#7 | |
New Member
VU Tuan-Long
Join Date: Jan 2018
Posts: 6
Rep Power: 8 |
Quote:
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