CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   Turbulence Intensity (http://www.cfd-online.com/Forums/fluent/37012-turbulence-intensity.html)

Luis June 21, 2005 07:18

Turbulence Intensity
 
I have a little problem,

I don't know exactly what the turbulence intensity parameter means.

I have a sistem similar like a cilindrical pipe with an object inside it. I set a value of 0.05 as Turbulence Intensity parameter at the pressure inlet and pressure outlet of my system, and when the simulation finishes, the average-wheighted area report in several planes (perpendicular to the pipe axis)shows me values up to 100%.

Anybody can tell me why I am getting that values?

The turbulence intensity value is relative to another parameter, and for that reason my results are up to 100%?

Thanks

Luis

Jonas Larsson June 21, 2005 09:25

Re: Turbulence Intensity
 
Yea, this is one of the most confusing things in Fluent. In boundary conditions turbulence intensity is computed as the RMS value of the local turbulent velocity fluctuations divided by the local mean velocity. However, when you report or plot things the turbulent intensity is computed as the RMS value of the local turbulent velocity fluctuations divided by a reference velocity (set to 1 m/s as default, can be changed in the reference settings). To compute the real local turbulent intensity you can define a UDS as SQRT(2/3*turbulent_energy)/velocity and plot/report that instead.

Hossain June 28, 2005 14:29

Turbulent Kinetic Energy
 
Turbulent Kinetic Energy defination is required


All times are GMT -4. The time now is 05:34.