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-   -   Periodic pressure gradient. (http://www.cfd-online.com/Forums/fluent/110589-periodic-pressure-gradient.html)

A7A December 15, 2012 02:24

Periodic pressure gradient.
 
Hi,

I am modelling a 3d periodic flow of air in a tube with wire coil insert (using relizable k-e model), and after 1500 iterations i get a good results of Nusselt number compared to the experimental results, but the friction factor(which is computed this way: f=(dp)/(0.5*density*velocity^2*(length/tube diameter))
is so high compared to the experimental results.:confused:

Could you give me any advice about this problem.

Thank you in advance

A7A December 15, 2012 09:32

Any ideas?:confused:

A7A December 25, 2012 04:13

Could you give me any solutions, untill now i couldnt manage to solve this problem.:confused:

Thank you in advance.

Kamu January 15, 2013 09:38

Quote:

Originally Posted by A7A (Post 398955)
Could you give me any solutions, untill now i couldnt manage to solve this problem.:confused:

Thank you in advance.

Which value of dp do you use for calculation of f? the correct value should be the pressure gradient under the periodic boundaries panel, you have to multiply it by the length of your tube.

A7A January 15, 2013 11:27

Thank you Kamu for your reply :), but there is no need to multiply dp by tube length because its divided by length in f correlation.


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