InterFoam and Rayleigh Breakup
 

Dears,
I want to simulate the case proposed at "https://doi.org/10.1016/j.compfluid.2011.05.010"
I attached the Geometry here .
They mentioned that the inside Gas is CO2 and its Pressurised @ 60 bar.the fluid that injected in the domain is water . for Simulating this case in openFoam , i had trouble in assigning boundary conditions. the walls and inlets are clear to me . but they used Neumann for outlet and its complicated for me. how should i apply 60bar for this (which boundary conditions should i use ?)