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?

U can create the same geomety using thin surface, that will be ideal one

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.

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

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"?

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.

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