Fluids

Fluids

Difference between using kinetic theory and UDF for mixture mass diffusivity

    • yijecho
      Subscriber

      Hi,


      I have an udf code for the mass diffusivity of a mixture, which is based on the kinetic theory of Chapman. The horizontal flow goes through a channel, which has an attached porous zone on the top. There are four species in my model.


      When I used the kinetic theory option for mass diffusivity, there is a species concentration difference between the porous zone and channel because of the viscous resistance of the porous zone. However, when I used the udf code, there is no difference between the two zones.


      What would be the reason for this?


      code


    • Weiqiang Liu
      Subscriber

      Hi, 


      I can't help you with your detained case. I can only tell you fluent can loop mixture species automatically. In other words, you can treat index i in DEFINE_DIFFUSIVITY macro as a variable. 


      Besides, I used THREAD_ID to assign different mass diffusion coefficients in different zones. Some author would use coordinates to determine zones. However, I think THREAD_ID is more convinient.


      Best 


       

    • emeredi
      Subscriber
      hello,nI hope you have solved your problem, it is very interesting and helped me in my, which was how to access the Kinetic Theory Parameters to be able to write a binary diffusion macronIf not, I suggest you look deep at your UDF and make a debug using VC++ for visual studio.nsend a message if you needn
Viewing 2 reply threads
  • You must be logged in to reply to this topic.