Karthik R
Administrator

Hello, 


How many cell zones do you have in your model? Are they two - water and roller (solid)? Have you assigned the respective material properties to these cell zones? If you have, Fluent will automatically know that you have water in your computational domain.


Or did I misunderstand your question and you are solving a multiphase problem with two fluids - air and water? If this is the case, you should be able to patch a certain region with the volume fraction corresponding to that of water.


Hope this helps.


Best,


Karthik