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.

Re: a problem with UDF
 

hi, I have similar problems. if anyone know, think in advance.

Re: a problem with UDF
 

Hi,

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,

Ale

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.

Hi

ap

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??

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.

Hi

ap