Fluids

Fluids

DEFINE_PROPERTY simple UDF

    • Diogo Martinho
      Subscriber

      Dear all,

      I am a new user of Fluent and of UDFs. I think this is quite simple comparing to other UDFs I have seen. However, I can't run it. 
      I am working with the eulerian model and I have a channel where some gas will be produced on one of the walls. I am also using the potential equation on my model. So, I would like the electrical conductivity of my primary phase (water) would change according to the presence of gas - Bruggeman Correlation. 
      When I try to compile it I have a warning and three errors. 

      Can anyone help me to solve my issue? 

      Best regards,



    • Rob
      Ansys Employee

      You may want to check the C_VOF macro for Eulerian: which phase are you monitoring? 

    • Diogo Martinho
      Subscriber

      Dear Rob,

      The alpha in this case would be the secondary phase.

    • Rob
      Ansys Employee

      Is it? Where did you set it? Note, the property UDFs are for that material, the solver then determines how much of that material is where and calculates any mixture properties from the material fraction & value. 

    • Diogo Martinho
      Subscriber

      It would be in theory. There I am not sure. But what I would like to have there it would be my gas (secondary phase) but now I am a bit lost. 
      Because the conductivity that I want to change is indeed the main primary phase (water) so it would be 

      sigma = sigma_zero*(1-alpha)^1.5 where alpha would be the volume fraction of the secondary phase.
      I hope this makes sense.

    • Rob
      Ansys Employee

      Sort of. However, you also have conductivity of the second phase(s) so you need to be careful you're not accounting for the volume fraction twice. 

    • Diogo Martinho
      Subscriber

      I see what you meant. Thank you very much for that input! 

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