Simulating a vena contracta
 

Hello,
first of all I'm terribly sorry about my poor english. I just hope you'll be able to understand what my problem is. Thanks in advance to all those who will try to help me. I appreciate it so much.
I'm trying to simulate in CFX 13 a nozzle used to accellerate water. Obviously the water jet doesn't have a cilindrical shape right outside the nozzle. I would like to know how I can simulate the water's behaviour when it interacts with the air in order to calculate the coefficient of contraction (Cc).
ANY kind of help will be extremely appreciated.
Bye. :)

So is the flow a free surface simulation? If so, have you done the free surface example tutorrials? They show you how to set up free surface simulations.

The water flow exits the nozzle and moves through the air reducing its cross section. It means it's a free surface simulation? No, I'm sorry, I've not done any free surface example tutorial. Where can I find them?
Thanks a lot!

Yes, this is a free surface simulation.

For tutorials on this go to the tutorials provided in the CFX documentation. "Free surface flow over a bump" is one you should look into closely.

There's a lot of new stuff here :eek: But, of course, if I want lo learn to use this amazing program, that's exactly what I need!
Thanks so much for your advices. I have to find the way to study ALL these tutorials.
Thanks again ;)