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

Cavitation in compressible flow

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 20, 2013, 15:18
Default Cavitation in compressible flow
  #1
New Member
 
CFDLife
Join Date: Apr 2009
Posts: 7
Rep Power: 8
soni7007 is on a distinguished road
Hello,

I am simulating compressible flow in an injector with liquid phase.
When the flow converges, I define the vapor phase and turn ON the cavitation (Reyleigh-plesset), and set a saturation pressure.

I have repeated this whole simulation with Incompressible flow also.

Now, in an incompressible case, the flow rate before i turn on the cavitation is different from after. Also, the high negative pressures (globally and locally) that were seen before cavitation disappear and the lowest pressure is set to the saturation pressure. This looks good to me.

However, in the Compressible flow case, the flow rates before and after the cavitation are more or less the same. Also, the high negative pressure do not go away.
This is my problem. Can someone explain why the negative pressures are not adjusted to the saturation pressure in the case with compressible flow.
Also, any explanation for different behavior of the flow rates?


Both the solutions are converged.

Thank you in advance.
soni7007 is offline   Reply With Quote

Old   March 20, 2013, 15:22
Default In addition
  #2
New Member
 
CFDLife
Join Date: Apr 2009
Posts: 7
Rep Power: 8
soni7007 is on a distinguished road
Also,
Boundary conditions:
Inlet = Total Pressure
Outlet = Pressure

I get this warning when i turn on the cavitation during Compressible flow:

"This compressible multiphase simulation has more than 1 continuos phase and uses a total pressure boundary condition. The total static pressure conversion will be made assuming an incompressible equation of state"

What does this mean?
soni7007 is offline   Reply With Quote

Old   March 20, 2013, 17:32
Default
  #3
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,826
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Can you explain what you are doing? Also post an image. Are you injecting a liquid through an injector into an air stream? Is the air or liquid compressible? Why does it need to be compressible?
ghorrocks is offline   Reply With Quote

Old   March 29, 2013, 13:06
Default
  #4
mic
New Member
 
Join Date: Mar 2009
Location: Milan, Italy
Posts: 12
Rep Power: 8
mic is on a distinguished road
Hi soni7007, a clearer explanation of your problem can help.
As far as my experience, I tried to simulate an injector for diesel engine application (compressible liquid) with Simerics. Also in cavitating situations, the results were good and physically reasonable.
mic is offline   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
compressible flow calculation error using rhoSimpleFoam solver student4326 OpenFOAM 6 February 10, 2012 10:36
Compressible flow, no data at the outlet mireis FLUENT 1 July 28, 2010 05:22
Compressible Fluid Flow in COMSOL Multiphysics BBG Main CFD Forum 1 November 19, 2008 15:05
compressible flow computation amv Main CFD Forum 5 June 27, 2003 07:27
Solving unsteady compressible low speed flow atit Main CFD Forum 8 July 31, 2000 13:19


All times are GMT -4. The time now is 12:25.