Perforated Plate and its porosity

Using SimScale
1

What is the ‘Free area ratio’ in Perforated Plate? Is this the Optical or the Aerodynamic Porosity number?

See for the difference (Figure 8): Gonzales, Howell B. et al.: Porosity and drag determination of a single-row vegetative barrier (Maclura pomifera). In: Transactions of the ASABE 61 (2018), issue 2, pp. 641-652.

I would have thought that in CFD one uses the Aerodynamic Porosity, but if I look at the info around Perforated Plate’s Porosity I see that it is the ‘Free area ratio’ (which sounds very optical;-).

<I ask it because my simulates come closer to measurements in the field when using Aerodynamic Porosity (derived from the Optical Porosity>

Thanks for your help.

2

Hi,

The perforated plate model, as the name suggests, assumes that you have a perforated plate. Using it for other types of porous media may not be the best idea.

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You can find the formulation used in this book.

3

I can understand it is not a match (my porous box of 2.2x25x0.35m and porous in the 0.35 direction); is in reality a fence made of bamboo stocks with an air gap in between. The optical porosity being 0.2 or 0.5. So I had hoped it is close to a perforated plate.

But I know, simulate reality is not easy.

Thanks for the link to the book.

All the best,