radiation

enzo

I have a rectangular empty incubator made of walls in anodized aluminium(black body) and glass.Inside there is air.I am using the DO model and so I must define the absorption ,scattering coefficient and refractive index.I'm using these values: air: abs.coef.=0;scat.coeff.=0;ref.index=1. aluminum(black body):abs.coeff.=1;scat.coef.=?(I don't know it);ref.index= ? glass: abs.coeff.=0.9;scat.coeff.= ?;ref.index=1.5. But these values are dimensionless,instead Fluent defines abs.coeff. and scattering coeff. as 1/L. L is thickness of my walls?

Thanks