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 difuse 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 steradians integration in a set of discrete directions represented by their direct cosines and corresponding weights for all .
The SLW model will change the spectral integration in a weighted sum of gray-gases represented by their absorption coefficient and corresponding weights for all .

Thus, the resulting RTE-SLW-DOM problem for emitting-absorbing non-scattering medium stands as below :

where is the radiative intensity for the virtual gray-gas in direction and is the blackbody radiative intensity.

The dimensional radiative source term and boundary net radiative heat flux are defined as :

where is the Stefan-Boltzmann constant, is the boundary emissivity and is the normal to the wall pointing out of the domain.

This radiative solver implementation considers only 3D cartesian problems under MPI cartesian domain decomposition approach.

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 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.

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 ()

This quadrature leads to 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 in [].

Default value = Fluid_Properties%Reference_Temperature

Href

Type : Real value.

Reference Length in [].

Default value = Nondimensionalization%Reference_Length

WallEmissivity

Type : Real array of size 6.

Boundaries emissivities 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. )

.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 used in the SLW model.

NbGas 1 : gray-gas assumption with = ka_min

NbGas 2 : SLW model is employed

Default value = 1

ka_min , ka_max

Type : Real values

These options set the lower and upper bounds of dimensional absorbing coefficient [] for the SLW model.

if NbGas 1 : = ka_min, ka_max is useless

if NbGas 2 : ka_min < < ka_max for all

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 2 (SLW model).

if “NbGas” $=$ 1 : useless

Available values :

“H2O” : mixture

“CO2” : mixture

Default value = “H2O”

xaref

Type : Real value

This option set the reference molar fraction 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 of the absorbing species in the overall domain.

if NbGas $=$ 1 : useless

Default value = 0.07

Pref

Type : Real value.

Reference pressure in [].

if “NbGas” $=$ 1 : useless

Default value = obtained from Fluid_Properties quantities