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Baz July 24, 2003 15:48

a problem with UDF
Hi, I have a problem with interpreted UDF . I wrote a simple initialization function for density gradient and after I initialize the solution, I can see contours of variable density. But, even after one iteration the density changes into constant. Why? Thank you for help.

ccc July 24, 2003 22:56

Re: a problem with UDF
hi, I have similar problems. if anyone know, think in advance.

Ale July 25, 2003 05:12

Re: a problem with UDF

perhaps I didn't get the point, but that's what I think: If you initialize a variable, however you do that, you give an initial approximation of the solution. If your model doesn't change the density during the calculation, and you've set a constant value for density in the Materials panel, at the second iteration you'll get that value in all the domain.

You should probably write a DEFINE_PROPERTY macro in your UDF, defining the law of change of your density during the simulation.

Good luck,


ap July 25, 2003 09:53

Re: a problem with UDF
I agree with Ale.

If you keep constant the density in Material properties, FLUENT will use your initialization value just to compute the first iteration.



Lola July 26, 2003 18:39

Re: a problem with UDF
I thought after 'first iteration', the solution is NOT 'converged'. Why would I bother checking any solution in some intermediate iterations??

ap July 27, 2003 19:22

Re: a problem with UDF
I'm not telling the solution is converged after the first iteration.

I just say that if you initialize a density value, but you keep constant density in the material properties, FLUENT will use the value specified there (Material properties) to do all computation except for the first iteration.



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