I'm trying to model a cavitating flow with the first versione of fluent 6. I've a pressure inlet of about 90 bar and an outlet of 2 bar with a meatus of 0.5mm (it's an homogenizing valve). I've tried with an unst simulation bringing the pressure outlet from 85 bar to 2 bar with a udf. The time step is 0.02 s and for 6s. The underelaxx: 0.3 for momentum, 0.1 for pressure, 0.001 for vap mass,0.1 for volume fract, 0.8 for all turbolence parameter.The bubble number=9e6. Segregated solver, k-e realizable,second order upwind for all the eq, Standard pressure coupling. If I use incompressible gas model for the vapour the solution seems to converge but the pressure still remains negative (-240 bar!!!!) and the vapour is in "high" pressure zones. If I use the compressible model the solution diverges at about 40 bar.

Hi!

Check your time step size...it should be much much smaller! about 0.00001 s...

By MATEUS

Thank you, Mateus! If you visit Parma, tell me... a good piece of ParmigianoReggiano is waiting for you! Bye