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April 7, 2012, 11:06 |
momentum loss
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#1 |
New Member
suong
Join Date: Apr 2012
Posts: 7
Rep Power: 14 |
hi
Can someone tell me: how to calculate energy or momentum of fluid loss behind the cylinders. ( flow past the cylinder) thank so much! |
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April 7, 2012, 16:19 |
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#2 |
Member
banty
Join Date: Mar 2012
Posts: 52
Rep Power: 14 |
Hi,
U can write a UDF for energy calculation at particular time E = (rho* Velocity*Velocity)/2 |
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April 8, 2012, 10:18 |
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#3 |
New Member
suong
Join Date: Apr 2012
Posts: 7
Rep Power: 14 |
Thank a lot, and I think i must spent more time to learn UDF. i'm a beginner
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April 8, 2012, 13:16 |
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#4 | |
Senior Member
Join Date: Jul 2009
Posts: 260
Rep Power: 17 |
Quote:
That's not the exact command because you have to define that point in either Fluent or in CFD post. If you want to calculate the average momentum or energy in a volume, you need to cut that volume out of the domain. If that's what you want to do, I'll help further. |
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April 8, 2012, 22:49 |
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#5 |
New Member
suong
Join Date: Apr 2012
Posts: 7
Rep Power: 14 |
Thank a lot kingjewel1. Yes, i want to calculate the average momentum or energy . Can use help me how to cut that volume out of the domain and how to calculate it, more detail, please..
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April 9, 2012, 05:25 |
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#6 |
Senior Member
Join Date: Jul 2009
Posts: 260
Rep Power: 17 |
When you say you want to calculate the average momentum loss behind a cylinder what exactly do you mean? can you draw it for us?
Is it the momentum you want to calculate in a given volume behind the cylinder? If that's the case what you need to do is decide what size this volume needs to be and the bounding coordinates (x0 y0 z0) and (x1 y1 z1). Go to Adapt -Region - Put in those coordinate and click MARK. Then go to Mesh -Separate- Zones choose the two fluid zones you want to split and that's your volume created. It's still perfectly transparent to the fluid, just has a separate name. Then go to Report/Volume/Volume-Average choose which volume you want to calculate in (ie your new one) and then choose your variable. Since you have a particular equation, you need to define this first in Custom Field Functions for it to appear in the list available in report. You can also set this as a volume monitor during calculation eg for a convergence criterium. Hope that helps. |
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April 11, 2012, 07:55 |
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#7 |
New Member
suong
Join Date: Apr 2012
Posts: 7
Rep Power: 14 |
thank you for replying
it is very useful. I did it. |
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