CFD Online Discussion Forums - Perforated sheet with hexagonal holes!?

Hi

I want some good literature on performance of perforated sheet with hexagonal holes. While Idelchik's "Handbook of Hydraulic Resistance" has abundant information about circular hole patterns, it has no mention of hexagonal holes.

Entire day of searching and I could stumble upon just two references. One is a published paper claiming hexagonal holes produce smaller pressure drop than circular ones, and other is a patent (yea, I have to search patents now, in the absence of literature :rolleyes:) which claims the velocity distribution for hex holes is smooth etc.

I want some good literature beforehand that gives resistance coefficients $\left( \zeta =\frac {\Delta P} {\frac{1}{2} \rho v^2} \right)$ for different percentages of open areas and thickness to hole diameter ratio etc, or at least something. I can always do a unitary cell symmetric arrangement of hexagonal hole to understand the characteristics, but it is time consuming and it is not possible to cover all types of perf sheets in limited time.

Thanks
OJ