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-   -   Divergence and reverse flow (http://www.cfd-online.com/Forums/fluent/114549-divergence-reverse-flow.html)

sihaqqi March 13, 2013 05:55

Divergence and reverse flow
 
1 Attachment(s)
Hi All

My geometry are two pipes connected at right angle to each other.

Condition 1:
In Boundary conditions, when I put my mean velocity, hydraulic dia and intensity in inlet and same in outlet except that pressure is 0, my simulation runs well giving results.

Condition 2:
When I give velocity profile, k, epsilon from UDF which is a copy of UDF in UDF manual for fluent, solution immediately diverges.

Therefore I start calculating with inlet values in condition 1 and interrupt in middle, and then put in condition 2 values, i.e profile values, but I am constantly getting reverse flow. Solution is not converging.

Does anyone know what my problem can be. Flow enters inlet vertically in +Y direction and then turns in +x direction. I shall be grateful for your positive response. I have attached my UDF file in case anyone wants to have a look at it. Please right click on it and click edit to open in notepad.

Regards

mqasimali March 13, 2013 17:51

check out your operating pressure, if it is compressible flow then you need to work on it and if incompresible then take it as low as possible

sihaqqi March 14, 2013 06:40

Hello Qasim

Can you please advise what effect can reducing operating pressure bring on reverse flow and convergence. How does it work in the equations?

I have reduced my pressure and it is still not working. Can you please have a look at my udf. This is my first time of making a UDF file.

Regards


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