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Old   March 13, 2013, 05:55
Default Divergence and reverse flow
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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.

Attached Files
File Type: c udf.c (2.2 KB, 22 views)
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Old   March 13, 2013, 17:51
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Qasim Ali
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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
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Old   March 14, 2013, 06:40
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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.

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