[darsh2198]

Hello all, I am trying to find out Rayleigh number for my experiment comprising of Metal foam with known porosity and pore density(PPI). I want to incorporate the permeability but am going through a hard time deciding what correlation to use from the available literature.
Also, in every correlation, they have used pore diameter and porosity; so how do I convert my Pore density to Pore diameter? While surfing I came across the following,

Dpore=4*(Dparticle*porosity)/[6*(1-porosity)]

Poredensity (ppcm)=(300/Dparticle)*sqrt[(1-porosity)^2/(porosity*pi)]

Are these true as I am unable to find any publication regarding this and if these are true, what are the units of the diameters?