FDS Source: Clarify BACK_EMISSIVITY for HT3D

Author: mcgratta

Manuals/FDS_Verification_Guide/FDS_Verification_Guide.tex

@@ -5022,6 +5022,39 @@ \section{SFPE Verification Cases}
 
 The Society of Fire Protection Engineers (SFPE) has developed a standard entitled {\em S.02 -- Calculation Methods to Predict the Thermal Performance of Structures \& Fire Resistive Assemblies}~\cite{SFPE_S.02} that contains an appendix with verification cases to benchmark basic heat transfer calculations. This section contains several of these cases.
 
+\subsection{Case 1: Lumped Mass Subjected to Standard Fire}
+\label{SFPE_Case_1}
+
+A plate ($\rho=7850$~kg/m$^3$, $c=0.52$~kJ/(kg~K), $\epsilon=0.7$) that has a thickness of 4~cm and an initial temperature of 20~°C is heated on the top and bottom surfaces according to the standard ISO~834 fire curve
+\be
+   T(t) = T_\infty + 345 \, \ln \left( 8t/60 + 1 \right) \label{ISO_834}
+\ee
+where the time, $t$, is in seconds. If the thermal conductivity of the material is relatively large, the temperature in the section can be taken as uniform. For the convection heat transfer coefficient, $h=25$~W/(m$^2$~K), calculate the temperature of the plate as a function of time (Fig.~\ref{fig:SFPE_Case_1}).
+
+\begin{figure}[ht]
+\centering
+\includegraphics[height=2.2in]{SCRIPT_FIGURES/SFPE_Case_1}
+\caption[The SFPE heat transfer verification Case 1]{Temperature of a 4~cm thick plate that is heated top and bottom by the standard fire curve.}
+\label{fig:SFPE_Case_1}
+\end{figure}
+
+\FloatBarrier
+
+\subsection{Case 2: Lumped Mass Subjected to Incident Flux}
+\label{SFPE_Case_2}
+
+A 1~cm thick horizontal flat plate ($\rho=7850$~kg/m$^3$, $c=0.56$~kJ/(kg~K), $\epsilon=0.9$) with an initial temperature of 20~°C is exposed from above with a radiant heater set to an incident flux of ̇50~kW/m$^2$. The gas temperature is 20~°C and $h=12$~W/(m$^2$~K). Assuming that the bottom and sides of the plate are perfectly insulated, and that the thermal conductivity of the material is sufficiently large to assume a uniform temperature with depth, calculate the temperature of the plate as a function of time (Fig.~\ref{fig:SFPE_Case_2}).
+
+\begin{figure}[ht]
+\centering
+\includegraphics[height=2.2in]{SCRIPT_FIGURES/SFPE_Case_2}
+\caption[The SFPE heat transfer verification Case 2]{Temperature of a 1~cm thick plate that is heated on top via an incident flux and insulated below.}
+\label{fig:SFPE_Case_2}
+\end{figure}
+
+\FloatBarrier
+
+
 \subsection{Case 6: 2-D Heat Transfer with Cooling by Convection}
 \label{SFPE_Case_6}
 
@@ -5039,11 +5072,7 @@ \subsection{Case 6: 2-D Heat Transfer with Cooling by Convection}
 \subsection{Case 7: 2-D Heat Transfer by Convection and Radiation}
 \label{SFPE_Case_7}
 
-A 0.2 m by 0.2 m square column ($k=1$~W/(m~K), $\rho=2400$~kg/m$^3$, $c=1$~kJ/(kg~K), $\epsilon=0.8$) is heated according to the ISO~834 time-temperature curve
-\be
-   T(t) = T_\infty + 345 \, \ln \left( 8t/60 + 1 \right) \label{ISO_834}
-\ee
-where the time, $t$, is in seconds. Assuming that $h=10$~W/(m$^2$~K) and that the initial temperature is $T_\infty=273$~K, calculate the temperature at the column center, corner and middle side surface as a function of time (Fig.~\ref{fig:SFPE_Case_7}).
+A 0.2 m by 0.2 m square column ($k=1$~W/(m~K), $\rho=2400$~kg/m$^3$, $c=1$~kJ/(kg~K), $\epsilon=0.8$) is heated according to the ISO~834 time-temperature curve, Eq.~(\ref{ISO_834}). Assuming that $h=10$~W/(m$^2$~K) and that the initial temperature is $T_\infty=273$~K, calculate the temperature at the column center, corner and middle side surface as a function of time (Fig.~\ref{fig:SFPE_Case_7}).
 
 \begin{figure}[ht]
 \centering

Source/read.f90

@@ -8338,7 +8338,6 @@ SUBROUTINE READ_SURF(QUICK_READ)
    SF%DUCT_PATH            = DUCT_PATH
    SF%DT_INSERT            = DT_INSERT
    SF%E_COEFFICIENT        = E_COEFFICIENT
-   IF (SF%HT_DIM>1 .AND. EMISSIVITY>=0._EB .AND. EMISSIVITY_BACK<0._EB) EMISSIVITY_BACK = EMISSIVITY
    SF%EMISSIVITY           = EMISSIVITY
    SF%EMISSIVITY_BACK      = EMISSIVITY_BACK
    IF (SF%EMISSIVITY>=0._EB) THEN

Source/wall.f90

@@ -2116,7 +2116,9 @@ SUBROUTINE SOLID_HEAT_TRANSFER(NM,T,DT_BC,PARTICLE_INDEX,WALL_INDEX,CFACE_INDEX,
 
    ! Compute back side emissivity
 
-   IF (SF%EMISSIVITY_BACK_SPECIFIED) THEN
+   IF (SF_BACK%EMISSIVITY_SPECIFIED) THEN
+      EMISSIVITY_BACK = SF_BACK%EMISSIVITY
+   ELSEIF (SF%EMISSIVITY_BACK_SPECIFIED) THEN
       EMISSIVITY_BACK = SF%EMISSIVITY_BACK
    ELSEIF (BACKING /= INSULATED) THEN
       CALL GET_EMISSIVITY(ONE_D,NWP,EMISSIVITY_BACK)

Utilities/Matlab/FDS_verification_dataplot_inputs.csv

@@ -612,6 +612,8 @@ d,realizable_mass_fractions,Flowfields/realizable_mass_fractions_git.txt,Flowfie
 d,rms_example,Controls/rms_example_git.txt,Controls/rms_example.csv,1,2,Time,mean|sd,Expected Mean|Expected RMS,k--|r--,0,100000,,5,20,-1.00E+09,1.00E+09,0,Controls/rms_example_devc.csv,2,3,Time,u|u_rms,FDS (u)|FDS (u\_rms),k-|r-,0,100000,,5,20,-1.00E+09,1.00E+09,0,rms\_example,Time (s),Velocity (m/s),0,20,1,0,2.5,1,no,0.05 0.90,NorthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/rms_example,Relative Error,mean,4.00E-02,Controls,mx,m,TeX
 d,screen_drag_1,Sprinklers_and_Sprays/screen_drag_1_git.txt,Sprinklers_and_Sprays/screen_drag_1.csv,1,1,Time,Exact 0.1|Exact 0.4|Exact 0.8,Exact 0.1|Exact 0.4|Exact 0.8,ko|ro|bo,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Sprinklers_and_Sprays/screen_drag_1_devc.csv,2,3,Time,FDS 0.1|FDS 0.4|FDS 0.8,FDS 0.1|FDS 0.4|FDS 0.8,k-|r-|b-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Screen Pressure Drop,Time (s),Pressure Drop (Pa),0,4,1,0,150,1,no,0.05 0.90,East,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/screen_drag_1,Relative Error,end,0.03,Sprinklers and Sprays,bs,b,TeX
 d,screen_drag_2,Sprinklers_and_Sprays/screen_drag_2_git.txt,Sprinklers_and_Sprays/screen_drag_2.csv,1,1,Time,Exact 0.1|Exact 0.4|Exact 0.8,Exact 0.1|Exact 0.4|Exact 0.8,ko|ro|bo,0,100000,,6,10,-1.00E+09,1.00E+09,0,Sprinklers_and_Sprays/screen_drag_2_devc.csv,2,3,Time,FDS 0.1|FDS 0.4|FDS 0.8,FDS 0.1|FDS 0.4|FDS 0.8,k-|r-|b-,0,100000,,6,10,-1.00E+09,1.00E+09,0,Screen Pressure Drop,Time (s),Pressure Drop (Pa),0,10,1,0,1500,1,no,0.05 0.90,East,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/screen_drag_2,Relative Error,mean,0.08,Sprinklers and Sprays,bs,b,TeX
+d,SFPE_Case_1,Heat_Transfer/SFPE_Case_1_git.txt,Heat_Transfer/SFPE_Case_1.csv,1,2,Time,Temperature,Exact,ko,0,100000,,0,100000,-1.00E+09,1.00E+09,20,Heat_Transfer/SFPE_Case_1_devc.csv,2,3,Time,Temperature,FDS,k-,0,100000,,0,100000,-1.00E+09,1.00E+09,20,SFPE Case 1,Time (s),Temperature (°C),0,30,60,0,1200,1,no,0.05 0.90,SouthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/SFPE_Case_1,Relative Error,end,0.01,Heat Transfer,bs,b,TeX
+d,SFPE_Case_2,Heat_Transfer/SFPE_Case_2_git.txt,Heat_Transfer/SFPE_Case_2.csv,1,2,Time,Temperature,Exact,ko,0,100000,,0,100000,-1.00E+09,1.00E+09,20,Heat_Transfer/SFPE_Case_2_devc.csv,2,3,Time,Temperature,FDS,k-,0,100000,,0,100000,-1.00E+09,1.00E+09,20,SFPE Case 2,Time (s),Temperature (°C),0,15,60,0,1200,1,no,0.05 0.90,SouthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/SFPE_Case_2,Relative Error,end,0.01,Heat Transfer,bs,b,TeX
 d,SFPE_Case_6,Heat_Transfer/SFPE_Case_6_git.txt,Heat_Transfer/SFPE_Case_6.csv,1,2,Time,Temperature,Exact,ko,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Heat_Transfer/SFPE_Case_6_devc.csv,2,3,Time,T,FDS,k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,SFPE Case 6,Time (s),Temperature (°C),0,1,1,0,1200,1,no,0.05 0.90,East,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/SFPE_Case_6,Relative Error,end,0.01,Heat Transfer,bs,b,TeX
 d,SFPE_Case_7,Heat_Transfer/SFPE_Case_7_git.txt,Heat_Transfer/SFPE_Case_7.csv,1,2,Time,Center|Side|Corner,Exact Center|Exact Side|Exact Corner,ko|ro|go,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Heat_Transfer/SFPE_Case_7_devc.csv,2,3,Time,Center|Side|Corner,FDS Center|FDS Side|FDS Corner,k-|r-|g-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,SFPE Case 7,Time (min),Temperature (°C),0,180,60,0,1200,1,no,0.05 0.90,SouthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/SFPE_Case_7,Relative Error,end,0.01,Heat Transfer,bs,b,TeX
 d,SFPE_Case_8,Heat_Transfer/SFPE_Case_8_git.txt,Heat_Transfer/SFPE_Case_8.csv,1,2,Time,Center|Side|Corner,Exact Center|Exact Side|Exact Corner,ko|ro|go,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Heat_Transfer/SFPE_Case_8_devc.csv,2,3,Time,Center|Side|Corner,FDS Center|FDS Side|FDS Corner,k-|r-|g-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,SFPE Case 8,Time (min),Temperature (°C),0,180,60,0,1200,1,no,0.05 0.90,Best,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/SFPE_Case_8,Relative Error,end,0.01,Heat Transfer,bs,b,TeX