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

Specifying fluid density

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 2, 2009, 02:51
Default Specifying fluid density
  #1
New Member
 
Sanjib Das Sharma
Join Date: May 2009
Posts: 22
Rep Power: 17
sanjibdsharma is on a distinguished road
Hi,

I am new to OpenFoam. I am trying to solve a steady-state, turbulent flow case with water as the fluid. Although I can change the fluid viscosity in the transportProperties file, there is no option for changing the fluid density. As the transportProperties file and the simpleFoam case was developed for air, I suspect my results are wrong as I did not change the fluid density. How do I change the fluid density from the default value?

Thanks in advance,

Sanjib
sanjibdsharma is offline   Reply With Quote

Old   July 2, 2009, 03:54
Default
  #2
Senior Member
 
Mark Olesen
Join Date: Mar 2009
Location: https://olesenm.github.io/
Posts: 1,714
Rep Power: 40
olesen has a spectacular aura aboutolesen has a spectacular aura about
Quote:
Originally Posted by sanjibdsharma View Post
Although I can change the fluid viscosity in the transportProperties file, there is no option for changing the fluid density.
For incompressible cases, there is no need for the fluid density.
OpenFOAM solvers just use the kinematic viscosity instead of dividing the dynamic viscosity by the fluid density. This saves a few operations and should thus improve the efficiency.
olesen is offline   Reply With Quote

Old   February 22, 2011, 09:55
Default and in compressible solvers?
  #3
Member
 
Aldo Iannetti
Join Date: Feb 2010
Posts: 48
Rep Power: 16
aldo.iannetti is on a distinguished road
Quote:
Originally Posted by olesen View Post
For incompressible cases, there is no need for the fluid density.
OpenFOAM solvers just use the kinematic viscosity instead of dividing the dynamic viscosity by the fluid density. This saves a few operations and should thus improve the efficiency.
Hi, I'm curious about what happens in compressible solvers, I mean:

- In incompressible solvers the pressure solution is to be multiplied by density (constant) in order to give you the real forces on the body.

-does libforces.so give you the real forces without multiplying the pressur e field?

Thanks

Aldo
aldo.iannetti 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
Which solver I should use when density of the fluid is not a constant dbxmcf OpenFOAM Running, Solving & CFD 0 March 25, 2007 05:26
REAL GAS UDF brian FLUENT 6 September 11, 2006 09:23
How to apply negtive pressure to outlet bioman66 CFX 5 June 3, 2006 02:40
Warning 097- AB Siemens 6 November 15, 2004 05:41
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 10:11


All times are GMT -4. The time now is 01:51.