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

Any ideas?:confused:

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.

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.

Cfx
 

Hi, this way had totally help me with this kind of problem but what about CFX. how can I estimate pressure gradian between two periodic zones. I first guess is to use CFD-Post but with what variable?