[moeinvh]

Hi friends,

I wanna use a non-gray model for combustion. As it is mentioned in Fluent Theory Guide, "The weighted-sum-of-gray-gases model (WSGGM) cannot be used to specify the absorption coefficient in each band.", I want to use a UDF to calculate absorption coefficient for each band, separately.
I found a macro in Fluent UDF manual which is named DEFINE_WSGGM_ABS_COEFF.

An example:

include "udf.h"
#include "materials.h"
DEFINE_WSGGM_ABS_COEFF(user_wsggm_abs_coeff, c, t, xi, p_t, s, soot_conc, Tcell, nb, ab_wsggm, ab_soot)
{
Material *m = THREAD_MATERIAL(t);
int ico2 = mixture_specie_index(m, "co2");
int ih2o = mixture_specie_index(m, "h2o");
real CO2_molf, H2O_molf;
real k2, k3, k4;
CO2_molf= xi[ico2];
H2O_molf= xi[ih2o];
switch (nb)
{
case 0 : /* First gray gas*/
{
*ab_wsggm = 0;
}
break;
case 1 : /* Second gray gas*/
{
k2 = 0.1;
*ab_wsggm = (k2 * (H2O_molf + CO2_molf)) * p_t;
}
break;
case 2 : /* Third gray gas*/
{
k3 = 7.1;
*ab_wsggm = (k3 * (H2O_molf + CO2_molf)) * p_t;
}
break;
case 3 : /* Fourth gray gas*/
{
k4 = 60.0;
*ab_wsggm = (k4 * (H2O_molf + CO2_molf)) * p_t;
}
}
*ab_soot = 0.1;
}

In this UDF the final value of absorption coefficient for each band is calculated by the product of a basic absorption coefficient (k2, k3, k4) in the sum of partial pressures of H2O and CO2.

Do you know any reference that could give me the values of basic absorption coefficients (k2, k3, k4) for various infrared and visible bands?

Best Regards,
Moein Vh