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Old   October 2, 2000, 22:26
Default Cavitation Simulation by CFD
  #1
Liu, L.
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Hi everyone.

I'm trying to simulate the cavitation flow( steady or transient) in a hydroturbine impeller using my own code(SIMPLE algorithm) as well as by commercial software of TASCFlow or STAR-CD, which are available at hand. The cavitation model I am considering to use at the moment is sheer bubble cavitation model, which, I considered, is relatively simpler comparing to some other existing models.

The problem is that I am not so familiar to TASCFlow or STAR-CD software package. I do not know if it is possible to incorporate the cavitation model I desired into either of these CFD softwares and how to do, such as where is the interface or options.

Has anyone got any experience with this kind of problem? I would be very grateful for any recommandations or information concerning to my problems --- the algorithm, the cavitation model, and, especially, the use of TASCFlow or STAR-CD for cavitation prediction.

Thanks very much in advance.
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Old   October 3, 2000, 04:39
Default Re: Cavitation Simulation by CFD
  #2
Jas
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Hello,

If you can write your cavitation model in fortran you can use it in starcd directly. All you have to do is choose the cavitation switch (there is a tutorial included for the cavitation approach) and then specify 'user' when you choose your model. You then write 'user' files which are compiled by prostar and are referenced by the solver each iteration to calculate cavitation properties.

All cell information is available for you to check etc

Regards
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Old   October 4, 2000, 16:11
Default Re: Cavitation Simulation by CFD
  #3
ken elms
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There`s a paper-parametric study of the cavitation inception behaviour of a mixed flow pump impeller using a 3d potential flow model -fedsm97-3374[asme] which may prove helpful.
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Old   October 5, 2000, 01:03
Default Re: Cavitation Simulation by CFD
  #4
Liu, L.
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Hello, ken elms,

Thanks for your information. Is fedsm97-3374[asme] a paper about this model? If it is, what does 'fedsm' mean and how to get it?

Thank you all who respond the message in this thread.
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Old   October 16, 2000, 04:22
Default Re: Cavitation Simulation by CFD
  #5
Niklas Wikstrom
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Hi Liu, The referred paper on potential flow cav. simulation is probably not very close to what you need to get into viscous simulation with eg. Star. I suppose the StarCD model is based on 'VoF' interface capturing (volume of fluid) with source terms for the fraction variable proportional to some pressure difference, and I would sugest for example Kunz et. al. (search at Penn state university www for pdf-docs.) Also Kubota-92 may serve as a good lead. I am very interested in your progress. What kind of model do you use in your own code? Mail me if you want more references.

(FEDSM: Fluid Enginering Division Summer Meeting (ASME-proceedings), Anual. very good.)

/Niklas
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Old   October 17, 2000, 10:30
Default Re: Cavitation Simulation by CFD
  #6
Jas
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Hello,

Another method you could use if you don't want to write your code in fortran is to choose 'user' for your model in starcd and then from within the user subroutine call your program. Then read your program output into the starcd variables and bobs your uncle.

regards

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Old   October 26, 2000, 11:53
Default Re: Cavitation Simulation by CFD
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Jas
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No comment...
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Old   November 1, 2000, 21:26
Default Re: Cavitation Simulation by CFD
  #8
Lijun Liu
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Hi Niklas,

Thank you very much for the response to my problem. Your information is very useful for my present work, I think. I tried to mail you but the email was bounced back. Are you sure your email address of niklasw@chalmers.se is still valid?

To get some basic results of cavitation flow in pump on its performance, I am incorporating the sheet cavitation model (attached cavitation bubble) in my code. As the first step, I deal it as steady cavitation flow (Like the work of R.Hirschi et al., J. of Fluids Engineering, vol.120, 1998). Then I would like to move my work to unsteady cases(sheet cavitation model by CFD), on which I have not seen any reference by now.

But my final aim is to study cavitation phenomena by the way like those of the two-phase flow models or the method of VOF, because the sheet cavitation model is very limited in application. In this case, the work of Kubota-92 is a good lead, as you said. But, as I know, all these models face a common difficulty --- its numerical unstability due to steep gradient of fluid properties in the flow. So I would like to read more references on this topic and wish to find a good technique to get this problem over.

BTW, how can I find the work of Kunz et. al? Did you mean I can find it from the homepage of Penn state university? Are you working on the same field of cavitation?

I will contact you about the progress of my work. Please keep in touch. My email address is

LJLiu@mech.kyutech.ac.jp or lijun_liu70@hotmail.com

Again, thank you very much.

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