The problem of modeling free jet with VOF

river

My task is to model a water free jet with a velocity of 10m/s from a round nozzle(d=8mm) spurting up into a cylinder(d=80mm) full of air.

Mesh:2d symmetric structural mesh,14000

Multiphase model:VOF

Viscous Model:standard k-e

Discretization:Quick

time step:1e-5

The problem is when the jet reached a certain height (time=1.2e-2),the continuity residual curve can't convergence,so I appled a less time-step(1e-6),bu soon it divergenced again.It seems like the jet will never get to its highest point.

I have little experience wirh FLUENT.I don't know what cause the problem and why it is so.Is there someone can give me a hand? Thank you.

I can sent the case file if nessary.