Diffusion coefficient for tracer simulation in ANSYS CFX?

- May 18, 2022 at 7:48 am
  
  Isar
  Subscriber
  
  I am simulating the residence time distribution in a simple pipe using tracer simulation. I use an additional variable as the tracer.
  I would like to know if I don't insert the diffusion coefficient in the simulation does CFX consider a predefined number or just ignore the diffusion term in the passive scalar simulation?
  
  Thank you!
- June 30, 2022 at 3:57 pm
  
  rfblumen
  Ansys Employee
  
  See "1.2.12.1. Kinematic Diffusivity" in the CFX Modeling Guide. Molecular kinematic diffusivity is a function of both the properties of the fluid and the medium that the Addition Variable represents, therefore there is no default value. If you don't set kinematic diffusivity it will be neglected.

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