Merge pull request firemodels#13999 from drjfloyd/master

FDS Source: Remove YY0 add WARNING for BACK and SPEC MASS_FRACTION_0 …

Source/read.f90

@@ -2924,7 +2924,6 @@ SUBROUTINE READ_SPEC
    SS%SIG                         = SIGMALJ
    SS%SPECIFIC_HEAT               = SPECIFIC_HEAT*1000._EB
    SS%REFERENCE_ENTHALPY          = REFERENCE_ENTHALPY*1000._EB
-   SS%YY0                         = MAX(0._EB,MASS_FRACTION_0)
    SS%REAL_REFRACTIVE_INDEX       = REAL_REFRACTIVE_INDEX
    SS%COMPLEX_REFRACTIVE_INDEX    = COMPLEX_REFRACTIVE_INDEX
 
@@ -3277,13 +3276,15 @@ SUBROUTINE READ_SPEC
       WRITE(MESSAGE,'(A)') 'ERROR(101): Problem with BACK input'
       CALL SHUTDOWN(MESSAGE) ; RETURN
    ENDIF
-
+IF (ANY(SPECIES_MIXTURE%ZZ0 > 0._EB)) THEN
+   WRITE(MESSAGE,'(A)') 'WARNING: BACK is being used and one or more SPEC have MASS_FRACTION_0 set.'
+   IF (MY_RANK==0) WRITE(LU_ERR,'(A)') TRIM(MESSAGE)
+ENDIF
 DO NS=1,MAX_SPECIES
    IF (SPEC_ID(NS)/='null') THEN
       DO N1=1,N_TRACKED_SPECIES
          IF (SPECIES_MIXTURE(N1)%ID==SPEC_ID(NS)) THEN
             SPECIES_MIXTURE(N1)%ZZ0 = MASS_FRACTION(NS)
-            IF (SPECIES_MIXTURE(N1)%SINGLE_SPEC_INDEX > 0) SPECIES(SPECIES_MIXTURE(N1)%SINGLE_SPEC_INDEX)%YY0 = MASS_FRACTION(NS)
             EXIT
          ENDIF
       ENDDO

Source/type.f90

@@ -498,7 +498,6 @@ MODULE TYPES
 TYPE SPECIES_TYPE
 
    REAL(EB) :: MW=0._EB                           !< Molecular weight (g/mol)
-   REAL(EB) :: YY0=0._EB                          !< Inital mass fraction
    REAL(EB) :: RCON                               !< Gas constant divided by molecular weight, \f$ R_0/W \f$ (J/kg/K)
    REAL(EB) :: MASS_EXTINCTION_COEFFICIENT=0._EB  !< Light extinction coefficient (m2/kg)
    REAL(EB) :: SPECIFIC_HEAT=-1._EB               !< Specific heat input by user (J/kg/K)