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June 29, 2011, 04:16 |
pipe
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#1 |
Senior Member
hamid
Join Date: Nov 2010
Posts: 185
Rep Power: 15 |
Hi Guys
in pipe with pressure boundary condition is it needed to have long domain? or any arbitrary length of pipe is fine for numerical calculation, |
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June 29, 2011, 07:17 |
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#2 |
New Member
eddy
Join Date: Apr 2011
Posts: 8
Rep Power: 15 |
as far as i know u dont need any specific length for solve ur problem, but if u want to see the full developed flow u need a certain length
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June 29, 2011, 08:55 |
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#3 |
Senior Member
hamid
Join Date: Nov 2010
Posts: 185
Rep Power: 15 |
In modeling fluid flow in a pipe, when do I need to see the fully developed flow? (either of laminar or turbulent regime)
Do I need specific length in inlet or outlet? What is the criterion for that? I was thinking that if after any modeling there wouldn’t be any circulation (which cause back flow) in openings the length is enough (either of inlet or outlet), is it true? |
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June 29, 2011, 09:53 |
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#4 |
New Member
eddy
Join Date: Apr 2011
Posts: 8
Rep Power: 15 |
hi,
1. it depends on you if u want to see any full developed flow. For example u have something in ur pipe and want to see how ur fluid pass it and how turbulent it will be. 2. still as far as i know in fluent u dont need any specific length, the solver will give u same results so if u solve ur modell with 10m length and anothertime with 1m length, this first meter should allways have same values. 3. ur last sentence i dont get |
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June 29, 2011, 10:07 |
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#5 |
Senior Member
hamid
Join Date: Nov 2010
Posts: 185
Rep Power: 15 |
Thank u very much for reply, I think the main issue is if flow passing through opposite direction in openings or not, say, in inlet flow coming from inside the domain to outside and in case of outlet if flow coming from outside of the domain to inside … if it dosent happen then the simulation is correct from this point of view (regardless of whatever the length of the pipe is), u may correct me please if I am wrong,
Thanks in advance Hamid |
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June 29, 2011, 10:45 |
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#6 |
New Member
eddy
Join Date: Apr 2011
Posts: 8
Rep Power: 15 |
hi,
thats right, the flow dont come back from outside. but i guess if u have backflow in ur pipe, its possible that flow left pipe through inlet. Because i dont know it 100%,i guess i will try to simulate it in next time edit: hmm seems i was on wrong way ... if u look at image u see that there is a little bit diffrence Last edited by shimmyya; June 29, 2011 at 11:26. |
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June 29, 2011, 12:16 |
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#7 |
Senior Member
hamid
Join Date: Nov 2010
Posts: 185
Rep Power: 15 |
So.. u mean at same cross section there are different results for longer and shorter length of the pipe, ... if so how long do u use for a domain to get rid of this issue?
and what if u have only the boundary condition of short length ? (though this is not my case but just asking) |
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