Adding a missing term in the scalar transport equation

- March 23, 2023 at 9:56 pm
  
  Meyzeeh
  Subscriber
  
  Hi Everyone
  Can someone kindly explain in detail how I can easily add the term highlighted in the equation below to the general scalar transport equation in fluent since all the other terms are already accounted for?
- March 24, 2023 at 6:52 am
  
  SRP
  Subscriber
  
  Hi,
  Transport equation consists of unsteady term, convection term, diffusion term, and source term. Can you please explain what the underline term describes?
  Thank you
- March 24, 2023 at 7:43 am
  
  Meyzeeh
  Subscriber
  
  Hi
  The equation describes the transport of a radioactive gas called thoron an isotope of radon with a half-life of t1/2= 55.6 s. As seen from the equation all the other terms you mentioned are taken care of except for the extra term which accounts for the radioactive decay of the thoron. The λ is the decay constant of the thoron and is defined as λ= ln 2/t1/2= ln 2/(55.6 s) =1.25x10^-2 s^-1. I could probably include that term in the source term but I don't know how to edit the source term in the general transport equation in ansys cause I'm new to ansys. Please help
- March 26, 2023 at 7:27 pm
  
  Meyzeeh
  Subscriber
  
  Please help!
- March 27, 2023 at 6:08 am
  
  SRP
  Subscriber
  
  Hi,
  You can create a UDF using a macro DEFINE_SOURCE.
  For more details, I recommend you to refer to Fluent Customization manual: 2.3. Model-Specific DEFINE Macros (ansys.com)
  If you are not able to access the link, please refer to this forum discussion: https://forum.ansys.com/forums/topic/using-help-with-links/#latest
  Thank you
- March 29, 2023 at 8:59 am
  
  Meyzeeh
  Subscriber
  
  Hi,
  Thank you very much for your help. I will try that.

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