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July 4, 2007, 06:20 |
Hi to all
Can u please tell
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#1 |
Member
hadi tartoussi
Join Date: Mar 2009
Location: paris
Posts: 48
Rep Power: 17 |
Hi to all
Can u please tell me what is the difference betwwen Ubulk and Ubar (for a LES turbulent channel flow) and how to calculate it for a given Re-tau. Thanks in advance Hadi |
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July 4, 2007, 12:06 |
for the case of isothermal pla
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#2 |
Senior Member
Maka Mohu
Join Date: Mar 2009
Posts: 305
Rep Power: 18 |
for the case of isothermal plane channel flow:
In literature, Ubulk usually is a volume averaged velocity which is a single number while, Ubar is usually an averaged (more accurately, an integral of) velocity (in time (after reaching fully developed flow and in homogeneous directions (x, z))), so it is a function of wall normal coordinate (Y); one can obtain Ubulk from Ubar by: Ubulk=integral of (Ubar dy); where y is wall normal direction and Ubar is function of y; have a look at postChannel utility; If you are running your simulation by specifying Re_tau, then you are computing dimensionless variables. Try to derive the equations to be sure what are you doing. Have a nice day! Best regards, Maka. |
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July 5, 2007, 08:52 |
Thanks alot for ur explanation
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#3 |
Member
hadi tartoussi
Join Date: Mar 2009
Location: paris
Posts: 48
Rep Power: 17 |
Thanks alot for ur explanation.
But i am confused about Ubar in transportproperties (channelOodles solver) is it the centerline velocity? or bulk velocity? Actually i ran postchannel for channel395 tutorial and i have the same problem as urs posted on Monday, December 11 2006: (PostChannel: collapsed field result inconsistancy) can u please tell me how did u solve this problem? Thanks in advance regards Hadi |
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July 6, 2007, 07:44 |
Hi Hadi,
Ubar is the bulk v
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#4 |
Senior Member
Maka Mohu
Join Date: Mar 2009
Posts: 305
Rep Power: 18 |
Hi Hadi,
Ubar is the bulk velocity. I posted the solution of the postChannel problem in the message that you referred to. Please recheck the message to read the solution. Best regards, Maka |
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