CFD Online Discussion Forums

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   FLUENT (https://www.cfd-online.com/Forums/fluent/)
-   -   cavitation...I'm in a trouble! SOS (https://www.cfd-online.com/Forums/fluent/36062-cavitation-im-trouble-sos.html)

Student March 18, 2005 07:13

cavitation...I'm in a trouble! SOS
 
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.

mateus March 22, 2005 08:22

Re: cavitation...I'm in a trouble! SOS
 
Hi!

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

By MATEUS

Student March 24, 2005 07:30

Re: cavitation...I'm in a trouble! SOS
 
Thank you, Mateus! If you visit Parma, tell me... a good piece of ParmigianoReggiano is waiting for you! Bye


All times are GMT -4. The time now is 05:02.