ANSYS Fluent’s P-1 Radiation Model Equations

- August 4, 2019 at 9:06 am
  
  SK95
  Subscriber
  
  Hi everybody,
  
  I am currently implementing the P1 radiation model via UDF in Fluent and have therefore looked at the example "8.2.5.2. Implementing ANSYS Fluent's P-1 Radiation Model Using User-Defined Scalars" in the Ansys Fluent Customization Manual 18.2 (page 537). Can someone explain to me how to derive the formula 8.11?
  
  Many thanks in advance.
- August 5, 2019 at 10:32 am
  
  Rob
  Forum Moderator
  
  Check in the Theory Guide for the P1 model. Note, we may have taken models from external references so may state equations with a reference: you'll need to go and find those.
- August 5, 2019 at 12:51 pm
  
  SK95
  Subscriber
  
  Only the general equations of the P1 model are explained in the Theory Guide. I haven't found a hint in any of your guides/ manuals on how to get from eq. 8.8 and 8.9 to 8.11. Neither the Fluent Customization Manual nor the Theory Guide state any references which could hold further information.
- August 5, 2019 at 1:22 pm
  
  DrAmine
  Ansys Employee
  
  I think you need to make a literature review about the P-n models for radiation. How equation is derived is mentioned in the theory guide but not all steps are included.
- August 5, 2019 at 7:43 pm
  
  SK95
  Subscriber
  
  I already have done a literature review. Derivations of the equations of radiation in general as well as the PN and P1 - Model model are described in detail in standard works such as "Radiative Heat Transfer" by Modest and "Thermal Radiation Heat Transfer" by Howell et al. I know how to derive all the equations on that topic in the theory guide which includes equation 8.8 and 8.9. But I cannot find anything on the equations 8.10 and 8.11 which is why i assume that they were derived from ansys for the implementation in fluent.
- August 12, 2019 at 2:54 pm
  
  DrAmine
  Ansys Employee
  
  Sorry but we won't get to the details about implementation on this open community.