CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM (http://www.cfd-online.com/Forums/openfoam/)
-   -   Specifying fluid density (http://www.cfd-online.com/Forums/openfoam/65957-specifying-fluid-density.html)

sanjibdsharma July 2, 2009 01:51

Specifying fluid density
 
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

olesen July 2, 2009 02:54

Quote:

Originally Posted by sanjibdsharma (Post 221151)
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.

aldo.iannetti February 22, 2011 08:55

and in compressible solvers?
 
Quote:

Originally Posted by olesen (Post 221158)
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


All times are GMT -4. The time now is 21:41.