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

about reference pressure

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 13, 2011, 10:25
Default about reference pressure
  #1
New Member
 
Join Date: Jul 2009
Posts: 25
Rep Power: 8
adam2008 is on a distinguished road
Hi,
I have a question about reference pressure. In definition of idea gas, there is a tab of "reference state", and "Air Ideal Gas" in CFX material library uses 14.7psi (1atm) as reference pressure. In domain setting, we also need to set a reference pressure. My question is,
Do I must set this reference pressure in domain setting as 14.7psi also if I use "Air Ideal Gas" as fluid?
I usually set reference pressure in domain setting as "0 psi" for convenience because I am deal with absolute pressure (psia) all the time. I ask because I happend to read one sentence in CFX-help as below
"When using an ideal gas, it is important to set an appropriate reference pressure since some properties depend on the absolute pressure level."

Thanks for your answer
adam2008 is offline   Reply With Quote

Old   May 17, 2011, 08:03
Default
  #2
Member
 
Shenren Xu
Join Date: Jan 2011
Location: London, U.K.
Posts: 63
Rep Power: 6
Shenren_CN is on a distinguished road
Quote:
Originally Posted by adam2008 View Post
Hi,
I have a question about reference pressure. In definition of idea gas, there is a tab of "reference state", and "Air Ideal Gas" in CFX material library uses 14.7psi (1atm) as reference pressure. In domain setting, we also need to set a reference pressure. My question is,
Do I must set this reference pressure in domain setting as 14.7psi also if I use "Air Ideal Gas" as fluid?
I usually set reference pressure in domain setting as "0 psi" for convenience because I am deal with absolute pressure (psia) all the time. I ask because I happend to read one sentence in CFX-help as below
"When using an ideal gas, it is important to set an appropriate reference pressure since some properties depend on the absolute pressure level."

Thanks for your answer

You have to, if you want to calculate compressible flow. Because the flow variables depends on the absolute value of the pressure (reference pressure in the domain). I suppose you "usually set reference pressure to 0psi" because you usually run incompressible flow solver, where the reference pressure does not matter at all (meaning it does not affect your velocity field).
Shenren_CN 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
Calculation of the Governing Equations Mihail CFX 7 September 7, 2014 06:27
specify a reference pressure point in FD method? Rui Main CFD Forum 10 August 30, 2010 08:50
OpenFoam-1.7.x on Suse 11.2 (64bit) does not compile val46 OpenFOAM Installation 4 August 27, 2010 03:43
Compiling new Solver with wmake lin123 OpenFOAM 3 April 13, 2010 14:18
G95 + CGNS Bruno Main CFD Forum 1 January 30, 2007 01:34


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