flow and heat transfer of rarefied air

Jon

Hello, I am trying to develop a simple model to represent the flow and heat transfer of air in a very low pressure environment. I realize that I must implement a slip model, but I'm not sure how to accomplish this in FLUENT. The user's guide mentions that "Maxwell's models are adopted for these physical phenomena in FLUENT for their simplicity and effectiveness." However, there is no mention of how to implement the models.

Also, there are similar posts in this forum's archives, but no response has been posted. It seems like this is of interest to many researchers.

It seems like a difficult boundary condition to implement with a UDF, so I would like to implement with the program's controls if possible. Any help in clearing this up would be greatly appreciated. Thanks!