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

negative pressure in cfx

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 18, 2006, 12:13
Default negative pressure in cfx
  #1
flar.t
Guest
 
Posts: n/a
hello,

i try to build a simulation for a valve. the problem is that whatever i try i get negative pressures about -6kPa in some regions. as i belive pressure below -1kPa could not be possible because the reference pressure is 1kPa. i changed the setup to multiphase fluid with cavitation modelled. as expected in this regions the vapour is present while elsewhere water is dominant. the pressure shown with cavitation beeing set has only positive absolute pressure. therfore in the help file "Ansys CFX-Solver: Modelling" on page 178 is written that ansys clips the pressure values so that they are only positive though they are "less negative than if cavitation is not modelled". the noncliped values could be find under the variable "Solver Pressure" and there are again regions with -6kPa. Does this mean that the negativ values are commonly present and not an error of the solver than more an error of the modelling physics? is there a way to avoid this phenomenon? kind regards, flar.t
  Reply With Quote

Old   December 19, 2006, 00:20
Default Re: negative pressure in cfx
  #2
HekLeR
Guest
 
Posts: n/a
liquid in tension = negative absolute pressure

this is physical

physically the flow should cavitate however, it's a CFD solution.... refine the mesh and it should help
  Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Negative pressure in Eulerial multiphase model hongyingli FLUENT 0 September 5, 2011 06:29
[blockMesh] BlockMesh FOAM warning gaottino OpenFOAM Meshing & Mesh Conversion 7 July 19, 2010 15:11
negative pressure mAx FLUENT 0 January 25, 2006 15:31
Negative Pressure S Christopher CFX 2 October 6, 2005 19:14
what the result is negatif pressure at inlet chong chee nan FLUENT 0 December 29, 2001 06:13


All times are GMT -4. The time now is 19:12.