![]() |
programmer's documentation
|
The radiative boundary condition is based on the calculation of a new wall temperature. This temperature is computed with a thermal flux balance:
Therefore :
Code_Saturne
the flux is positive when it is oriented from inside to outside.Corps | Emissivity |
---|---|
polished steel | 0.06 |
oxidized steel | 0.80 |
steel rough | 0.94 |
polished aluminium | 0.04 |
oxidiezd aluminium (inside) | 0.09 |
oxidized aluminium (wet air) | 0.90 |
brick | 0.93 |
concrete | 0.93 |
paper | 0.8 to 0.9 |
water | 0.96 |
Boundary faces may be identified using the getfbr subroutine. The syntax of this subroutine is described in the cs_user_boundary_conditions subroutine, but a more thorough description can be found in the user guide.
The following initialization block needs to be added for the following examples:
At the end of the subroutine, it is recommended to deallocate the work array:
In theory Fortran 95 deallocates locally-allocated arrays automatically, but deallocating arrays in a symetric manner to their allocation is good pratice, and avoids using a different logic for C and Fortran.
Remaining initialisation
ivar: number of the thermal variable
Min and Max values for the wall temperatures (clipping otherwise)
and
are given in Kelvin.
We define zones of wall boundary, and we assign a type. This allows to apply the boundary conditions and realize balance sheets by treating them separately for each zone.
For each boundary face ifac (not just the faces of wall) the user defines his own choice by a number of zone izfrdp(ifac)
from color of the boundary face or more generally, their properties (color, groups ...), or boundary conditions specified in cs_user_boundary_conditions, or even of their coordinates.
izfrdp(ifac)
) is arbitrarily chosen by the user, but must be a positive integer and less than or equal to nbzrdm
(value set in parameter radiat::h).isothp(ifac)
boundary face typeitpimp
-> Gray wall with fixed inside temperatureipgrno
-> Gray wall with fixed outside temperatureiprefl
-> Reflecting wall with fixed outside temperatureifgrno
-> Gray wall with fixed conduction fluxifrefl
-> Reflecting wall with fixed conduction fluxtintp(ifac)
inside wall temperature (Kelvin) initialize thwall at the first time step. If isothp
= itpimp
, the value of thwall is fixed to tintp
In the other case, tintp
is only for initialization. rcodcl
= conduction fluxepsp
= emissivityxlamp
= conductivity ( epap
= thickness ( textp
= outside temperature ( Here is a list of examples:
For wall boundary faces, selection criteria: color 1
For wall boundary faces, selection criteria: color 2
For wall boundary faces, selection criteria: color 3
For wall boundary faces which have the color 4:
If the conduction flux is zero then the wall is adiabatic. The array has the value of the flux.
Flux density (< 0 if gain for the fluid)
For wall boundary faces which have the color 5:
and
If the conduction flux is zero then the wall is adiabatic. Flux density (< 0 if gain for the fluid)
For all boundary faces that are not wall it is MANDATORY to impose a number of zone in the array izfrdp
. For each zone, informations will be displayed in the listing.
Verification that all boundary faces have been treated