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

Pressure units in compressible solvers

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 12, 2010, 09:29
Default Pressure units in compressible solvers
  #1
Member
 
Costas K
Join Date: Nov 2009
Location: UK
Posts: 51
Rep Power: 17
thekay is on a distinguished road
Send a message via ICQ to thekay Send a message via MSN to thekay
Hi all and happy new year!

I was going through Wolle's thread about the motorbike tutorial: http://www.cfd-online.com/Forums/ope...k-out-box.html
He noticed that:
Quote:
In the 0/p file, the dimensions for p is set to [0 2 -2 0 0 0 0], what would be equivalent to (m*m)/(s*s) which is obviously not a pressure unit... How come?
and he got the reply from askjak that:
Quote:
The incompressible solvers in OpenFOAM solve the density normalized Navier-Stokes equation. The units corresponds to p/rho.
I now see in the tutorial /compressible/sonicFoam/laminar/forwardStep/ that the pressure units have:
dimensions [1 -1 -2 0 0 0 0];
which corresponds to kgr/(m*s^2).
Could somebody explain to me how this is derived?

Thank you very much in advance.

Kay
thekay is offline   Reply With Quote

Old   January 12, 2010, 09:45
Default
  #2
New Member
 
Join Date: Apr 2009
Posts: 26
Rep Power: 17
askjak is on a distinguished road
http://en.wikipedia.org/wiki/Pressure#Units, so kg/(m*s^2) is the SI unit of pressure.
askjak is offline   Reply With Quote

Old   January 12, 2010, 09:48
Default
  #3
Member
 
Costas K
Join Date: Nov 2009
Location: UK
Posts: 51
Rep Power: 17
thekay is on a distinguished road
Send a message via ICQ to thekay Send a message via MSN to thekay
Hmmm... Actually, I found it. My mistake obviously. Read "compressible" instead of incompressible in askjak's reply. Please delete.
thekay is offline   Reply With Quote

Reply


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
Calculation of the Governing Equations Mihail CFX 7 September 7, 2014 07:27
Pressure enigma. Sara Main CFD Forum 22 July 30, 2009 05:46
pressure correction in compressible flow Yijin Li Main CFD Forum 1 January 10, 2009 09:04
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 10:11
Hydrostatic pressure in 2-phase flow modeling (CFX4.2) HB &DS CFX 0 January 9, 2000 14:19


All times are GMT -4. The time now is 00:33.