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

Negative Total Pressure

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 13, 2008, 11:38
Default Negative Total Pressure
  #1
J
Guest
 
Posts: n/a
Here I am again...

In a simulation I found a negative total pressure in a contour plot... Anybody can explain me how it is possible???

Thanks

J
  Reply With Quote

Old   March 14, 2008, 11:28
Default Re: Negative Total Pressure
  #2
CycLone
Guest
 
Posts: n/a
The Total Pressure (aka Stagnation Pressure) is reported relative to your domain reference pressure. Don't confuse it with Absolute Pressure, which is the static pressure + relative pressure.

Also, if you fluid is incompressible, any pressure is possible. If fluid properties are not dependant on pressure, then all pressures are relative (i.e. if you add the same pressure, say Poffset, to all your boundary conditions, the solution is the same, but the pressure is offest).

In reality you don't have negative pressures because density changes with pressure in a gas and liquids boil/cavitate when the pressure is low enough. If you include this behavior in your model, you won't see negative pressures.

-CycLone
  Reply With Quote

Old   April 5, 2008, 07:24
Default Re: Negative Total Pressure
  #3
sivaramakrishnaiah
Guest
 
Posts: n/a
hi i am also faced same problam i give inlet mass flow==1kg/sec and static pressure= 8bar outlet avrage static pressure= 3bar i given. but when ever i seen post results plot is comming nearly 20 bat comming. how is rectifying. please give me responce thanking you bye

  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
negative pressure in cfx flar.t CFX 1 December 19, 2006 00:20
negative pressure mAx FLUENT 0 January 25, 2006 15:31
Negative Pressure S Christopher CFX 2 October 6, 2005 18:14
Total pressure to static pressure ratio roadracer CD-adapco 1 April 17, 2003 05:31
total pressure change in a pipe flow Im FLUENT 4 February 6, 2002 20:09


All times are GMT -4. The time now is 18:57.