CFD Online Discussion Forums

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   CFX (https://www.cfd-online.com/Forums/cfx/)
-   -   Pressure Loss Definition. (https://www.cfd-online.com/Forums/cfx/21527-pressure-loss-definition.html)

Chirag August 17, 2005 09:21

Pressure Loss Definition.
 
My problem domain has a sub domain (a perforated grid plate) in flow stream. For this, I know %age open area. How can I define it in CFX so that I can get exact flow behavior?

Indrajit August 17, 2005 09:37

Re: Pressure Loss Definition.
 
U can create the same geomety using thin surface, that will be ideal one

Chirag August 17, 2005 10:02

Re: Pressure Loss Definition.
 
Thanks Indrajit.

But, how will I define pressure drop or %age opening for a thin surface? Also I can't model thousands of holes on that surface (perforated grid plate), as that will increase mesh size tremendously.

Is there any other way out?

Thanks again.

Glenn Horrocks August 17, 2005 19:31

Re: Pressure Loss Definition.
 
Hi,

Use a momentum source, or possibly a porous material. This will give you a number of pressure loss models to choose from so you can select the most appropriate one.

Glenn Horrocks

Chirag August 18, 2005 00:51

Re: Pressure Loss Definition.
 
I am trying to do it with "Momentum Source/Porous Loss Model" only. But I do not understand how to define X, Y & Z Cartesian Components under "Directional Loss Model" (when only available data to you is %age opening in grid plate)? Also, what else shall be defined in "Linear Resistance Coefficient" / "Quadratic Resistance Coefficient"?

Michael Bo Hansen August 18, 2005 08:12

Re: Pressure Loss Definition.
 
I tend to use the Handbook of Hydraulic Resistance by Idelchik when I have to determine the pressure drop coefficient of grids and other flow restrictions.

Robin August 19, 2005 14:50

Re: Pressure Loss Definition.
 
With CFX 10.0 there is a new "Pourous" Domain object. This allows you to specify both the volume fraction and the pressure drop characteristics.

Regards, Robin


All times are GMT -4. The time now is 20:43.