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Old   February 6, 2007, 14:29
Default Cavitation
  #1
Juan Catelén
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Hello. I need some help. I am simulating a pipe with a restriction orifice and I want to see if there is cavitation. The fluid is water. I'm doing what is recommended: inlet with total pressure and an outlet with mass flow. But the program places a wall in the place where I have a fixed pressure. If I use opening instead, with the cavitation model on, after some iterations the program gives an overflow error. What should I do?? Bye and thanks in advance.

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Old   February 6, 2007, 17:00
Default Re: Cavitation
  #2
Glenn Horrocks
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Hi,

Do you just want to know whether cavitation is present or not, or do you want to know the size of the cavitation?

If you just want to know whether it is present or not you generally can turn all the cavitation and multiphase stuff off and just run single phase. In post-processing look at the minimum pressure and if it is below the fluid's vapour pressure you know that cavitation would be present.

The wall on the exit means there is recirculating flow at the exit. Have a look at the results to confirm this. You may have to move the downstream boundary further downstream.

Glenn Horrocks
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Old   February 6, 2007, 17:07
Default Re: Cavitation
  #3
Juan Catelén
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Thanks for the answer. I have seen that there is cavitation. Now I want to see the amount and what happend with the rest of the fluid. If I move the boundary downstream: is it better to draw the rest of the system as it actualy is or to simply make larger the the pipe? Bye. Thanks again.
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Old   February 7, 2007, 03:59
Default Re: Cavitation
  #4
Severin
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If the region further downstream affects the flow in the cavitation region (or the region where you have your outlet at the moment), I would model the actual downstream region. If this is not the case, you can simply make the pipe longer.
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