Not for the release SUNFLUIDH_EDU .
This data set is used to define the radiative problem. Otherwise, it can be omitted.
This module considers the Radiative Transfer Equation (RTE) for an emitting-absorbing non-scattering medium enclosed by diffuse boundaries.
To take into account the gas behavior, it considers both gray-gas assumption as well as real gas behavior through the Spectral-Line-Weighted-Sum-of-Gray-Gases (SLW) model.
The final RTE-SLW problem is then discretize with the Discrete Ordinates Method (DOM).
The DOM discretize the $4\pi$ steradians integration in a set of $M$ discrete directions represented by their direct cosines and corresponding weights $\vec{q_m} = (\vec{s_m},\omega_m) = (\mu_m,\eta_m,\xi_m,\omega_m)$ for all $m \in [1,M]$.
The SLW model will change the spectral integration in a weighted sum of $N_g$ gray-gases represented by their absorption coefficient and corresponding weights $(\kappa_j,a_j)$ for all $j \in [1,N_g]$.
Thus, the resulting RTE-SLW-DOM problem for emitting-absorbing non-scattering medium stands as below :
\begin{equation} \vec{s}_m \cdot \nabla I_j^m (x_i,\vec{s}_m) = \kappa_j \left[ a_j I_b({T}(x_i)) - I_j^m(x_i,\vec{s}_m) \right]; \quad \forall (m,j) \in [M,N_g] \end{equation}
where $I_j^m$ is the radiative intensity for the virtual gray-gas $j$ in direction $m$ and $I_b$ is the blackbody radiative intensity.
The dimensional radiative source term $S_r$ and boundary net radiative heat flux $q_r^{net}$ are defined as :
\begin{eqnarray} S_r(x_i,{T}) & = & - \sum_{j=0}^{N_g} \kappa_j \left[ \sum_{m=1}^{M} \omega_m I_j^m (x_i,\vec{s}_m) - 4 a_j \sigma_B ({T}(x_i))^4 \right] \\ {q}_r^{net}(x_i^{wall}) & = & \varepsilon_{wall} \left[ \sigma_B ({T}(x_i^{wall}))^4 - \sum_{j=0}^{N_g} \sum_{m:\vec{s}_m \cdot \vec{n} > 0} \omega_m |\vec{s}_m\cdot \vec{n}| I_j^m (x_i^{wall},\vec{s}_m) \right] \end{eqnarray}
where $\sigma_b$ is the Stefan-Boltzmann constant, $\varepsilon$ is the boundary emissivity and $\vec{n}$ is the normal to the wall pointing out of the domain.
&Radiative_Heat_Transfer_DOM activateRadiation = .false., RadiativePeriod = 1, FirstIterations = 20, RadiativeLocalIterations = 1, RadiativeConvergenceTolerance = 1.E-15, WallRadcoeff = 1.0 , VolRadCoeff = 1.0, RadiativeScheme = "STEP", ActivateGas = .false., NbGas = 1, ka_max = 0.0, ka_min = 0.0, Pref = 101325.0, Tref = 300., Href = 1, speca = "H2O", xaref = 0.07, xaUniform = 0.07, SQuad = 8, WallEmissivity = 0.0 0.0 0.0 0.0 0.0 0.0 /