Hello Rob. Thanks for your answer.

May I ask what do you mean by your comment? I do not find it clear. Which example? What do you mean by "Others in the Community aren't necessarily bound by the same rules as staff"?

I need a drag modification except Brucato as Brucato over predicts for gas-liquid flow. The only way there is to define a UDF, and doing that, I am not sure how I can call the drag coefficient being calculated by FLUENT (I use Grace model), to the code so I can multiply it to the modification coefficient I am defining in UDF. The only I found was to maybe embed the drag model in the code as well and then use the whole UDF as a Drag model instead of a modification model.

Another issue is that the interphase exchange coefficient which is given as K_pq in FLUENT theory guide, is also dependent on the drag coefficient and if I change drag coefficient, then I should also change K_pq.

In tutorial, there is no modification example in DEFINE-EXCHANGE-PROPERTY. I really appreciate any useful insight you can give me.