GROUP 1. Run title and other preliminaries
TEXT(Rad Transf From Hot Wall,TGAS=CST
TITLE
mesg(PC486/50 time last reported as appx. 9.sec
  DISPLAY
    This run analyses the radiative heat transfer from a hot wall
  to a gas which is assumed to be at a constant temperature TGAS.
  The gas participates in the heat transfer by absorbing and
  emitting radiation. The wall is treated as a grey body with an
  emissivity of 0.5. The results compare well with the analytical
  solution. Alternatively, the case can be solved using RADIAT
  command called from GREX3, the examples are provided in library
  cases 550-552.
 
      Hot wall        Warm gas: radiation source is sigma*T**4
     /_ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
    /|                 |
    /|                 |                                       |
    /|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
 
      ----->         Radiation cannot cross domain boundaries
        x
 
  ENDDIS
 
   ** The locally-defined variables are as follows:
 
            GSIGMA         Stefan-Boltzmann constant
            SCATCO         Scattering coefficient
            ABSORC         Absorption coefficient
            EMISS          emissivity of wall
            THOT           hot wall temperature
            TGAS           gas temperature
 
REAL(GSIGMA,SCATCO,ABSORC,EMISS,THOT,TGAS)
GSIGMA= 5.6697E-08; SCATCO=0.05;      ABSORC= 0.1
EMISS=0.5;          THOT  = 666.0;    TGAS  = 293.0
 
    GROUP 3. X-direction grid specification
IREGX=1; GRDPWR(X,5,1.0,1.0)
 
    GROUP 7. Variables stored, solved & named
   ** Take variable C1 for the x-directed radiation flux
SOLVE(C1);NAME(C1)=RAD
 
    GROUP 8. Terms (in differential equations) & devices
   ** The built-in source and convection terms are absent
TERMS(RAD,N,N,Y,N,Y,N)
 
    GROUP 9. Properties of the medium (or media)
   ** "Prandtl number" for radiation flux
PRNDTL(RAD) = (SCATCO+ABSORC)*ENUL
 
    GROUP 11. Initialization of variable or porosity fields
FIINIT(RAD)=GSIGMA*TGAS**4
    GROUP 13. Boundary conditions and special sources
   ** Radiation flux from hot wall
PATCH(HOT,WEST,#1,#1,#1,#1,#1,#1,1,1)
COVAL(HOT,RAD,EMISS/(2.0-EMISS),GSIGMA*THOT**4)
   ** Source of radiation flux due to emission or absorption by
     medium
PATCH(SOURCE,VOLUME,#1,#NREGX,#1,#1,#1,#1,1,1)
COVAL(SOURCE,RAD,ABSORC,GSIGMA*TGAS**4.)
    GROUP 15. Termination of sweeps
LSWEEP=2
    GROUP 21. Print-out of variables
NPRINT=LSWEEP; OUTPUT(RAD,Y,N,N,N,N,N)
    GROUP 23. Field print-out and plot control
PATCH(RADPLOT,PROFIL,1,NX,1,1,1,1,1,1);COVAL(RADPLOT,RAD,0.0,0.0)