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Mass Flow from expression problem

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Old   May 15, 2019, 15:08
Default Mass Flow from expression problem
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Ziga
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Hello,

I have this one problem. A little background: I have an empirical equation from which the mass flow is calculated. In the equation there are only constants, except for one, which is the pressure in a point, which I know how to read it etc. Nothing hard, except when I first wanted to do this with an UDF, but not even the Ansys Support knows why Fluent freezes in the moment you press Initialization.

They told me there is a option to do this over the Named Expressions, which I did. Basically it works fine, except it doesn't. The problem is Fluent reads the pressure in each iteration and calculates a new mass flow each time, which makes it to diverge. I need Fluent to only calculate the new mass flow each time step and not iteration. Any one knows if this is possible and if, how to do it? I just want to do 200-300 iteration in each time step before changing the inlet condition.

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Old   May 23, 2019, 15:14
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André
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Can you share the expression you have? Are you taking the average pressure over a surface?
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