#immersol)
#declare
   IMMERSOL 1D tem1, wall-patch
            Radiative heat exchange in a participating media.
            IMMERSOL-WALL treatment.
TEXT(IMMERSOL-WALL 1D for TEM1 & T3.    :206
#cls
  TITLE
  DISPLAY
  
  Heat is radiated from a hot wall to a cold though a participating
  medium, which is however supposed to possess zero conductivity, 
  set by making PRNDTL(TEM1) = 1.e10 .
  
  The medium therefore takes a temperature equal to T3, the 
  'radiation temperature'.
  
  The emissivities of the walls, which coincide with the outer 
  boundaries of the domain, are less than unity. The are set via
  PATCH, COVAL and SPEDAT commmands.
  
  The equations have an exact solution, to which the PHOENICS 
  solution conforms well.
  
  It is interesting to note that, when the medium is given a 
  finite conductivity, the radiant heat flux is increased.

  ENDDIS  
#pause  
  **************************************************************
   PHOTON USE
   AUTOPLOT
   FILE
   PHI 5
 
   CL;DA 1 TEM1;DA 1 T3;COL3 1;BLB4 2;REDR
   MSG    Temperature and T3 profiles.
   ENDUSE
  **************************************************************
#direct
#temps
MESG(  ENTER optical thickness Kr*Wg (default 1.):
READVDU(OPTHI,REAL,1.0)
WGAP = 1.0;  KGAS= 0.0258
KROSS= OPTHI/WGAP;  SCATT= 0.0;  EMISS= KROSS-SCATT
FIINIT(EMIS)=EMISS;FIINIT(SCAT)=SCATT
QRAD= SIGMA*(THOT**4-TCLD**4)
AEMISH= (1./EMISH-0.5)
AEMISC= (1./EMISC-0.5)
QRAD = QRAD/(0.75*OPTHI + AEMISH + AEMISC)
QRAD
TGH=(THOT**4-QRAD/SIGMA*AEMISH)**.25
TGH
TGC=(TCLD**4+QRAD/SIGMA*AEMISC)**.25
TGC
SOLVE(TEM1)
#geom2
#radflux
    *** Set diffusivities for TEM1 and T3 (i.e. PRNDTL() must be
        set to -Value). NOTE! value of diffusivity for T3 in a gas
        is not important (correct value is calculated by EARTH);
PRNDTL(TEM1)= -KGAS;  
PRNDTL(TEM1)= 1.e10 
INIADD= F;  FIINIT(TEM1)= (THOT+TCLD)/2.
  
    *** IMMERSOL-WALL settings (CO=GRND4 for T3; VAL=GRND4 for TEM1)
        NOTE! Coefficient for TEM1 must be set as for standard
        wall-patch, i.e. it might be GRND2 for turbulent flows.
COVAL(IMSWL1,TEM1,WALLCO,THOT)
COVAL(IMSWL1,T3,GRND4,THOT)
COVAL(IMSWL2,TEM1,WALLCO,TCLD)
COVAL(IMSWL2,T3,GRND4,TCLD)

SPEDAT(SET,EMISSIVITY,OF IMSWL1,R,:EMISH:)
SPEDAT(SET,EMISSIVITY,OF IMSWL2,R,:EMISC:)
    *********************
LSWEEP= 200; SELREF=F; RESREF(T3)= 1.E-3
IXMON=NX/2+1;IYMON=NY/2+1;IZMON=NZ/2+1;
NXPRIN=1; NYPRIN=1; NZPRIN=1
OUTPUT(LTLS,N,N,N,N,N,N); OUTPUT(WDIS,N,N,N,N,N,N)

VARMAX(T3)=THOT;VARMIN(T3)=TCLD
VARMAX(TEM1)=THOT;VARMIN(TEM1)=TCLD