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

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Old   March 18, 2005, 06:13
Default cavitation...I'm in a trouble! SOS
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Student
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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.
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Old   March 22, 2005, 07:22
Default Re: cavitation...I'm in a trouble! SOS
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mateus
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Hi!

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

By MATEUS
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Old   March 24, 2005, 06:30
Default Re: cavitation...I'm in a trouble! SOS
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Thank you, Mateus! If you visit Parma, tell me... a good piece of ParmigianoReggiano is waiting for you! Bye
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