CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Definition of pressure

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

LinkBack Thread Tools Display Modes
Old   August 15, 2001, 13:31
Default Definition of pressure
Ola Nordblom
Posts: n/a

I found the information given in the Fluent manual about pressure boundary conditions rather confusing. Can someone try to explain how the calculated pressure in FLUENT is defined, and how the hydrostatic pressure comes into the picture? I assume that my flow problem is incompressible.

Usually the hydrostatic pressure field is subtracted from the N.S. Equations in order to include the hydrostatic head into the body force term. The new pressure variable will then be equal to the basic one minus the hydrostatic pressure (based on some reference density). However, from the FLUENT manuals I get the impression that FLUENT adds the hydrostatic pressure, and that the solved pressure field will include the hydrostatic head. The manuals then say that the inputs of pressure at the boundary should not include hydrostatic pressure differences, which is confusing. Se the chapter about pressure boundary conditions.

Any information related to pressure definitions and pressure boundary conditions would be very helpful.

Thanks in advance,

Ola Nordblom
  Reply With Quote

Old   August 16, 2001, 15:58
Default Re: Definition of pressure
Posts: n/a
You define what your reference pressure is in the system. I always leave it at atmospheric. FLUENT does all its calcs with total absolute pressures. BUT, the inlet and outlet boundary conditions simply are the gage pressures relative to the reference. The manual is just letting you know that the software is programmed to assume you are entering gage pressure. As long as you enter in the correct reference pressure and boundary conditions, it will do the calcs from there.

good luck

  Reply With Quote


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
OpenFOAM static build on Cray XT5 asaijo OpenFOAM Installation 9 April 6, 2011 12:21
pressure BC-natural convection engahmed Main CFD Forum 0 June 16, 2010 11:38
Neumann pressure BC and velocity field Antech Main CFD Forum 0 April 25, 2006 02:15
Pressure Inlet yields wrong velocities Ben FLUENT 0 November 21, 2004 02:47
Pressure definition CFX Begineer CFX 4 October 18, 2002 11:31

All times are GMT -4. The time now is 09:47.