CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

cavitation

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   February 21, 2008, 18:15
Default cavitation
  #1
iceman
Guest
 
Posts: n/a
I do some cavitation simulation. And I would like to know what could I take for the value of the Fraction non condensable gaz (water vapor). I begin the simulation with the default value of Fluent and near the implosion I take a smaller value (fraction non condensable gaz)in order to find some good value of the pressure. But the transition is not good, the pressure field is very strange. In some zone I found high pressure value. Has somebody ever tried to change the fraction non condensable gaz and what kind of results did you obtain

Thanks,
  Reply With Quote

Old   February 21, 2008, 23:27
Default Re: cavitation
  #2
NRD
Guest
 
Posts: n/a
Hello,

I have never tried changing the fraction of non-condensable gases. However, I just wanted to share my thoughts. In my understanding cavitation can either be(i) vaporous (where the liquid evaporates whenever the local pressure drops below the vapor pressure) or (ii) gaseous cavitation (where the entrapped non-condensable gas acts as bubbles). If the gaseous cavitation is not important in your case you can neglect the effect of non-condensable gas. Cavitation will occur if the pressure falls to a value below the vapor pressure. Please correct me if I am wrong.
  Reply With Quote

Old   February 22, 2008, 03:56
Default Re: cavitation
  #3
iceman
Guest
 
Posts: n/a
In my case when I reduce the value of the fraction non condensable gas (1,5e-05 to 1e-08) I've got a factor 40 on the pressure pick value due to the collapse.
  Reply With Quote

Old   February 25, 2008, 06:40
Default Re: cavitation
  #4
mateus
Guest
 
Posts: n/a
If I remember correctly you're simulating a single bubble. I think the fraction of non condensable gas only makes sense when you're dealing with many bubbles (attached or developed cavitation) otherwise it should be 0. Also it's a question if mixture model is sinful for single bubble simulation - vof is probably more appropriate.

I hope I helped, MAteus
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cavitation Problems Chris CD-adapco 4 July 17, 2005 16:47
Cavitation inception problem newuser FLUENT 3 May 13, 2003 11:14
Cavitation Simulation by CFD Liu, L. CFX 2 November 29, 2000 14:50
Cavitation Simulation by CFD Liu, L. CD-adapco 2 November 1, 2000 22:51
Cavitation Simulation by CFD Liu, L. Main CFD Forum 7 November 1, 2000 22:26


All times are GMT -4. The time now is 23:17.