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sunfluidh:radiative_heat_transfer_dom_setup_namelist

Namelist "Radiative_Heat_Transfer_DOM"

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.

This radiative solver implementation considers only cartesian problems and does not support immersed bodies.

Full data set of the namelist

  &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 /

Definition of the data set for the DOM-RTE problem


activateRadiation

  • Type : Boolean value
  • This option activates the radiative module.
    • .false. : no radiation considered
    • .true. : radiation problem is considered
  • Default value = .false.

RadiativePeriod

  • Type : Integer value
  • This option set the periodicity of resolution of the Radiative problem in time iteration.
  • Default value = 1

FirstIterations

  • Type : Integer value
  • In the case that no restart fields are available (start radiation from scratch), the solver will iterates “FirstIterations” times before entering the time loop.
  • Default value = 20

RadiativeLocalIterations

  • Type : Integer value
  • Number of sub-iteration for the RTE solving at each radiative iteration.
  • Default value = 1

RadiativeConvergenceTolerance

  • Type : Real value
  • Convergence criteria on the wall Fluxes and radiative source term for the sub-iteration.
  • Default value = 1.E-15

WallRadcoeff

  • Type : Real value
  • Prescaler on the net radiative heat flux $q_r^{net}$ at walls.
  • For debugging only.
  • Default value = 1.0

VolRadcoeff

  • Type : Real value
  • Prescaler on the radiative source term $S_r$.
  • For debugging only.
  • Default value = 1.0

RadiativeScheme

  • Type : Character string with a maximum size of 20
  • Name of the interpolation scheme used in the Discrete Ordinates Method.
  • Available values :
    • “STEP” : first order interpolation scheme (robust)
    • “DIAMOND” : second order centered interpolation scheme (could lead to negative intensity)
    • “LATHROP” : second order interpolation scheme with limiter (time-consuming)
  • Default value = “STEP”

SQuad

  • Type : Integer value.
  • Order N of the level symmetric angular quadrature ($S_N$)
  • This quadrature leads to $M = (N+2)\times N$ directions in volume and half at boundaries
  • Available values are 2, 4, 6, 8, 10, 12, 14
  • Default value = 8

Tref

  • Type : Real value.
  • Reference temperature $T_{ref}$ in [$K$].
  • Default value = Fluid_Properties%Reference_Temperature

Href

  • Type : Real value.
  • Reference Length $H_{ref}$ in [$m$].
  • Default value = Nondimensionalization%Reference_Length

WallEmissivity

  • Type : Real array of size 6.
  • Boundaries emissivities $\varepsilon$ sorted as (x-,x+,y-,y+,z-,z+).
  • Default values = 0.0 0.0 0.0 0.0 0.0 0.0

Definition of the data set for the SLW model


activateGas

  • Type : Boolean value
  • This option activates the SLW module.
    • .false. : transparent medium under gray-gas assumption is considered (i.e. $\kappa = 0$)
    • .true. : Gas absorption and emission is considered
  • Default value = .false.
if activateGas == .false., the settings below are unnecessary.

NbGas

  • Type : Integer value
  • This option sets the number of weighted gray-gases $N_g$ used in the SLW model.
    • NbGas $=$ 1 : gray-gas assumption with $\kappa$ = ka_min
    • NbGas $\ge$ 2 : SLW model is employed
  • Default value = 1
Setting NbGas $=$ 1 and ka_min = 0 is equivalent to wall-to-wall radiation du to the presence of transparent medium

ka_min , ka_max

  • Type : Real values
  • These options set the lower and upper bounds of dimensional absorbing coefficient [$m^{-1}$] for the SLW model.
    • if NbGas $=$ 1 : $\kappa$ = ka_min, ka_max is useless
    • if NbGas $\ge$ 2 : ka_min < $\kappa_j$ < ka_max for all $j \in [1,N_g]$
  • Default value = [ ka_min , ka_max ] = [ 0.0 , 0.0 ]

SPECA

  • Type : Character string with a maximum size of 3
  • Name of the absorbing species when NbGas $\ge$ 2 (SLW model).
    • if “NbGas” $=$ 1 : useless
  • Available values :
    • “H2O” : $air-H_2O$ mixture
    • “CO2” : $air-CO_2$ mixture
  • Default value = “H2O”

xaref

  • Type : Real value
  • This option set the reference molar fraction $x_{ref}$ of the absorbing species for the SLW model.
    • if “NbGas” $=$ 1 : useless
  • Default value = 0.07

xaUniform

  • Type : Real value
  • As long as the SLW model is not coupled with species equations, this option set a uniform molar fraction $x_{a}$ of the absorbing species in the overall domain.
    • if NbGas $=$ 1 : useless
  • Default value = 0.07

Pref

  • Type : Real value.
  • Reference pressure $P_{ref}$ in [$Pa$].
    • if “NbGas” $=$ 1 : useless
  • Default value = obtained from Fluid_Properties quantities
sunfluidh/radiative_heat_transfer_dom_setup_namelist.txt · Dernière modification: 2016/12/14 18:42 de cadet