Absorption coefficient > 1 ?

Jamiro

Hi CFD friends!

I encoutered a kind of weird result in my pdf-combustion simulations (10 atm). Using the Discrete Ordinates Radiation Model with the WSGGM option, I got values of absorption coefficient up to 1.9! That seems to me apparently wrong, reminding the basic radiation law that the sum of absorption, transmission and reflection coefficients must be = 1. I point out that it's not a matter of grid dependency because it has been properly refined and values over 1 are spread all over the domain (and not within a confined region).

Anyone could give me an explanation: could these values make sense physically or are they definetely and anyway wrong? Are they somehow consistant with Fluent definition of absorption coefficient, which is dimensionally 1/m(lenght), whereas it should be adimensional?

Thanking you in advance.

Jamiro.