SpectraRust/synspec/extracted/rtedfe.f
2026-03-19 14:05:33 +08:00

169 lines
4.7 KiB
Fortran

SUBROUTINE RTEDFE
C =================
C
C Solution of the radiative transfer equation - frequency by
C frequency - for the known source function.
C
C The numerical method used:
c Discontinuous Finite Element (DFE) method
c Castor, Dykema, Klein, 1992, ApJ 387, 561.
C
C Input through blank COMMON block:
C CH - two-dimensional array absorption coefficient (frequency,
C depth)
C ET - emission coefficient (frequency, depth)
C
INCLUDE 'PARAMS.FOR'
INCLUDE 'MODELP.FOR'
INCLUDE 'SYNTHP.FOR'
PARAMETER (ONE=1.,TWO=2.,HALF=0.5)
PARAMETER (TAUREF = 0.6666666666667)
DIMENSION DT(MDEPTH),ST0(MDEPTH),AB0(MDEPTH),DELDM(MDEPTH),
* dtau(mdepth),rip(mdepth),rim(mdepth),riup(mdepth),
* AMU(3),WTMU(3),RINT1(MMU),
* AMUI(MMU),AMUW(MMU),TAU(MDEPTH),SS0(MDEPTH)
COMMON/RTEOPA/CH(MFREQ,MDEPTH),ET(MFREQ,MDEPTH),
* SC(MFREQ,MDEPTH)
COMMON/EMFLUX/FLUX(MFREQ),FLUXC(MFREQC)
COMMON/CONSCA/SCC1(mdepth),SCC2(MDEPTH)
COMMON/REFDEP/IREFD(MFREQ)
C
C angle points (AMU) and angular integration weights (WTMU)
C
DATA AMU/.887298334620742D0,.5D0,.112701665379258D0/,
* WTMU/.277777777777778D0,.444444444444444D0,.277777777777778D0/
C
DO I=1,ND-1
DELDM(I)=HALF*(DM(I+1)-DM(I))
END DO
C
c angle points
C
IF(IFLUX.EQ.0) THEN
NMUS=NMU
do i=1,nmu
amui(i)=amu(i)
amuw(i)=amu(i)*wtmu(i)
end do
ELSE IF(IFLUX.EQ.1) THEN
NMUS=NMU0
do i=1,nmus
amui(i)=angl(i)
amuw(i)=angl(i)*wangl(i)
end do
END IF
C
C overall loop over frequencies
C
DO IJ=1,NFREQ
FR=FREQ(IJ)
C
C total source function
C
DO ID=1,ND
AB0(ID)=CH(IJ,ID)
SCT=FRX1(IJ)*SCC2(ID)+FRX2(IJ)*SCC1(ID)
ST0(ID)=(ET(IJ,ID)+SCT)/AB0(ID)
SS0(ID)=-SCT/AB0(ID)
END DO
AH=0.
C
C optical depth scale
C
TAU(1)=0.
IREF=1
DO ID=1,ND-1
DT(ID)=DELDM(ID)*(AB0(ID+1)/DENS(ID+1)+AB0(ID)/DENS(ID))
TAU(ID+1)=TAU(ID)+DT(ID)
IF(TAU(ID).LE.TAUREF.AND.TAU(ID+1).GT.TAUREF) IREF=ID
END DO
IREFD(IJ)=IREF
C
C quantities for the lower boundary condition
C
FR15=FR*1.D-15
BNU=BN*FR15*FR15*FR15
PLAND=BNU/(EXP(HK*FR/TEMP(ND))-ONE)
DPLAN=BNU/(EXP(HK*FR/TEMP(ND-1))-ONE)
DPLAN=(PLAND-DPLAN)/DT(ND-1)
c
c loop over angle poits
c
DO I=1,NMUS
do id=1,nd-1
dtau(id)=dt(id)/amui(i)
enddo
C
c outgoing intensity
c
rip(nd)=PLAND+AMUI(I)*DPLAN
id=nd-1
dt0=dtau(id)
dtaup1=dt0+one
dtau2=dt0*dt0
bb=two*dtaup1
cc=dt0*dtaup1
aa=dtau2+bb
rim(id+1)=(aa*rip(id+1)-cc*st0(id+1)+dt0*st0(id))/bb
do id=nd-1,1,-1
dt0=dtau(id)
dtaup1=dt0+one
dtau2=dt0*dt0
bb=two*dtaup1
cc=dt0*dtaup1
aa=one/(dtau2+bb)
rim(id)=(two*rim(id+1)+dt0*st0(id+1)+cc*st0(id))*aa
rip(id+1)=(bb*rim(id+1)+cc*st0(id+1)-dt0*st0(id))*aa
enddo
do id=2,nd-1
riup(id)=(rim(id)*dtau(id-1)+rip(id)*dtau(id))/
* (dtau(id-1)+dtau(id))
enddo
riup(1)=rim(1)
riup(nd)=rip(nd)
c
AH=AH+AMUW(I)*RIUP(1)
RINT1(I)=RIUP(1)
rint1(i)=max(rint1(i),1.e-40)
c
c end of the loop over angle points
c
END DO
c
FLUX(IJ)=AH*HALF
if(iflux.ge.1) then
C
C output of emergent specific intensities to Unit 10 (line points)
C or 18 (two continuum points)
C
IF(IJ.GT.2) THEN
WRITE(10,618) WLAM(IJ),FLUX(IJ),(RINT1(IMU),IMU=1,NMUS)
ELSE
WRITE(18,618) WLAM(IJ),FLUX(IJ),(RINT1(IMU),IMU=1,NMUS)
END IF
end if
618 FORMAT(1H ,f10.3,1pe15.5/(1P5E15.5))
C
C if needed (if iprin.ge.3), output of interesting physical
C quantities at the monochromatic optical depth tau(nu)=2/3
C
IF(IPRIN.GE.3) THEN
T0=LOG(TAU(IREF+1)/TAU(IREF))
X0=LOG(TAU(IREF+1)/TAUREF)/T0
X1=LOG(TAUREF/TAU(IREF))/T0
DMREF=EXP(LOG(DM(IREF))*X0+LOG(DM(IREF+1))*X1)
TREF=EXP(LOG(TEMP(IREF))*X0+LOG(TEMP(IREF+1))*X1)
STREF=EXP(LOG(ST0(IREF))*X0+LOG(ST0(IREF+1))*X1)
SSREF=EXP(LOG(-SS0(IREF))*X0+LOG(-SS0(IREF+1))*X1)
SREF=STREF+SSREF
ALM=2.997925E18/FREQ(IJ)
WRITE(96,636) IJ,ALM,IREF,DMREF,TREF,STREF,SSREF,SREF
636 FORMAT(1H ,I3,F10.3,I4,1PE10.3,0PF10.1,1X,1P3E10.3)
END IF
C
C end of the loop over frequencies
C
END DO
RETURN
END