Porosity field in Fluent
 

Hi,

I modelling flow trough a porous medium. A wrote a UDF with the Ergun equation. I tested this UDF, and it is working when the porosity is constant. But in my project I need define not a constatnt value of porosity, but a scalar field (with small fluctuations of the porosity in each direction). I can not use the DEFINE_INIT function, because in Fluent a porosity variable is not present. For the same reason, I can not use it in a UDF (the Porosity value from the Porous Zone tab). For this reason, I defined a UDS. I can initialize now the UDS with DEFINE_INIT and after initialization the porosity field is correct (I can see it in post-processor). But, when the calculations begin, the porosity field changes. What can be the reason? I will only define a porosity field, and this field should be constant in time. I would add that I defined a very small value of the UDS Diffusitivity too (when is 0, than the Fluent can not benign calculations). I use Fluent in version 6.2.16.

Can someone help me?

Wojciech

Wojciech , have you solved your problem? really this time I have this problem , could you help me?
thanks
Sarah