Need help in Modeling of oil-water flow in A vertical Pipe
 

i'm using Mixture model to simulate the two phase flow in vertical pipe. My problem is "operating density". There is a place in operating conditions to specify the operating density so which value i should use?because it is having huge impact on total pressure drop. I used default value of fluent which is equal to density of air but in my simulation there is no air only oil and water. plz help.
Thanks.