coupling acoustic with fluid flow

hi,
I need to use "acoustic" and "fluid flow" modules to solve my problem.the only common dependent variable in this two is pressure .i want to couple this two to reach pressure field.do you know how i can do it?
in the fluid flow i should use turbulent flow.

my next question is about boundary condition in acoustic when i want to model an sonoreactor what is the boundary condition for ultrasonic tip?is there any mathematics that i should add to my physics?

I need your help.
Thanks in advance.
Amir