FDS Source: Allow TMP_GAS_FRONT and EXTERNAL_FLUX to co-exist

Manuals/FDS_User_Guide/FDS_User_Guide.tex

@@ -3330,7 +3330,7 @@ \subsection{Simulating the Cone Calorimeter}
 \item Create \ct{SPEC} lines to list any gas species created in the pyrolysis process. A \ct{REAC} line is not needed, as there is no gas phase combustion allowed.
 \item On the \ct{TIME} line, set \ct{WALL_INCREMENT=1} to force FDS to update the solid phase every time step (normally it does this every other time step), and set \ct{DT} to a value that is appropriate for the solid phase calculation. Since there is no gas phase calculation that will limit the time step, it is best to control this yourself.
 \item Generate \ct{MATL} lines, plus a single \ct{SURF} line, as you normally would, except add \ct{EXTERNAL_FLUX} to the \ct{SURF} line. This is simply a ``virtual'' source that heats the solid. Think of this as a perfect radiant panel or conical heating unit. You can control the \ct{EXTERNAL_FLUX} using either \ct{TAU_EF} or \ct{RAMP_EF}. This is useful if you want to ramp up the heat flux following ignition to account for the additional radiation from the flame. See Sec.~\ref{info:RAMP_Time} for more details about ramps. Note that if you want the \ct{EXTERNAL_FLUX} to {\em replace} all other sources of radiation at the surface, set \ct{SKIP_INRAD=T} on the \ct{SURF} line along with \ct{EXTERNAL_FLUX}.
-\item On the \ct{SURF} line, set a gas temperature, \ct{TMP_GAS_FRONT} (\unit{\degreeCelsius}), and optionally a \linebreak[4]\ct{HEAT_TRANSFER_COEFFICIENT} (\unit{W/(m^2.K)}), allowing you to control the convective heat flux from gas to surface and vice versa. Similar to \ct{EXTERNAL_FLUX}, \ct{RAMP_TMP_GAS_FRONT} and \ct{RAMP_HEAT_TRANSFER_COEFFICIENT} can be set to account for pre- vs. post-ignition conditions. Note that \ct{TMP_GAS_FRONT} and \ct{EXTERNAL_FLUX} should not be specified on the same \ct{SURF} line.
+\item On the \ct{SURF} line, set a gas temperature, \ct{TMP_GAS_FRONT} (\unit{\degreeCelsius}), and optionally a \linebreak[4]\ct{HEAT_TRANSFER_COEFFICIENT} (\unit{W/(m^2.K)}), allowing you to control the convective heat flux from gas to surface and vice versa. Similar to \ct{EXTERNAL_FLUX}, \ct{RAMP_TMP_GAS_FRONT} and \ct{RAMP_HEAT_TRANSFER_COEFFICIENT} can be set to account for pre- vs. post-ignition conditions.
 \item Assign the \ct{SURF_ID} to a \ct{VENT} that spans at least one grid cell.
 \item Add solid phase output devices to the solid surface, like \ct{'WALL TEMPERATURE'}, \ct{'TOTAL HEAT FLUX'}, \ct{'GAUGE HEAT FLUX'}, and \ct{'WALL THICKNESS'}. Use these to track the condition of the solid as a function of time. The generation rate of the various gases is output via the quantity \ct{'MASS FLUX'} along with the appropriate \ct{SPEC_ID}. Do not specify the quantity \ct{'BURNING RATE'} because FDS assumes that this is specific for fuel gas, and in this exercise there is no fuel gas.
 \end{enumerate}
@@ -14234,7 +14234,6 @@ \chapter{Error Codes}
 404  \> \ct{Row ... of ... has a bad complex index.} \> Section~\ref{radiative_part_props}  \\
 407  \> \ct{TABLE ... not found.} \> Section~\ref{info:spraypattern}  \\
      \>                                                                               \>                          \\
-420  \> \ct{SURF ... cannot have both EXTERNAL_FLUX and TMP_GAS_FRONT.} \> Section~\ref{info:simulating_the_cone_calorimeter} \\
 421  \> \ct{SURF ... cannot be applied to a thin obstruction ...} \> Section~\ref{info:thin_obstructions}  \\
 422  \> \ct{VENT ... cannot be applied to a thin obstruction ...} \> Section~\ref{info:thin_obstructions}  \\
 423  \> \ct{HT3D solid must have at least one face exposed ...} \> Section~\ref{info:HT3D_Limitations}  \\

Source/read.f90

@@ -8875,11 +8875,6 @@ SUBROUTINE READ_SURF(QUICK_READ)
    SF%TMP_GAS_FRONT = TMP_GAS_FRONT + TMPM
    SF%TMP_GAS_BACK  = TMP_GAS_BACK  + TMPM
 
-   IF (SF%EXTERNAL_FLUX>TWENTY_EPSILON_EB .AND. TMP_GAS_FRONT>-TMPM) THEN
-      WRITE(MESSAGE,'(3A)') 'ERROR(420): SURF ',TRIM(SF%ID),' cannot have both EXTERNAL_FLUX and TMP_GAS_FRONT.'
-      CALL SHUTDOWN(MESSAGE) ; RETURN
-   ENDIF
-
    IF (SF%TMP_GAS_BACK>0._EB) SF%BACKING = VOID
 
    ! Allocate parameters indexed by layer

Source/wall.f90

@@ -436,7 +436,7 @@ SUBROUTINE NEAR_SURFACE_GAS_VARIABLES(T,SF,BC,B1,LP,TW,WALL_INDEX,PARTICLE_INDEX
 
    IF (SF%TMP_GAS_FRONT > 0._EB) THEN
       B1%TMP_G = TMPA + EVALUATE_RAMP(T-T_BEGIN,SF%RAMP(TIME_TGF)%INDEX)*(SF%TMP_GAS_FRONT-TMPA)
-      B1%Q_RAD_IN = B1%EMISSIVITY*SIGMA*B1%TMP_G**4
+      IF (SF%EXTERNAL_FLUX<TWENTY_EPSILON_EB) B1%Q_RAD_IN = B1%EMISSIVITY*SIGMA*B1%TMP_G**4
    ELSE
       B1%TMP_G =  TMP(BC%IIG,BC%JJG,BC%KKG)
    ENDIF
@@ -447,7 +447,7 @@ SUBROUTINE NEAR_SURFACE_GAS_VARIABLES(T,SF,BC,B1,LP,TW,WALL_INDEX,PARTICLE_INDEX
 
    IF (SF%TMP_GAS_FRONT > 0._EB) THEN
       B1%TMP_G = TMPA + EVALUATE_RAMP(T-T_BEGIN,SF%RAMP(TIME_TGF)%INDEX)*(SF%TMP_GAS_FRONT-TMPA)
-      B1%Q_RAD_IN = B1%EMISSIVITY*SIGMA*B1%TMP_G**4
+      IF (SF%EXTERNAL_FLUX<TWENTY_EPSILON_EB) B1%Q_RAD_IN = B1%EMISSIVITY*SIGMA*B1%TMP_G**4
    ENDIF
 
    ! For thermally thick particles, interpolate near-surface quantities. B1%U_TANG interpolation is in part.f90