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mcgratta merged 3 commits into from
Jan 21, 2025
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FDS Source: Reduce QR_CLIP #14096

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5aabed2
FDS Source: Lower QR_CLIP to 1 kW/m3
mcgratta Jan 21, 2025
c45d4b4
Merge remote-tracking branch 'firemodels/master'
mcgratta Jan 21, 2025
24cff7b
FDS User Guide: Issue #13516. Add explannation of PYROLYSIS DEPTH
mcgratta Jan 21, 2025
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39 changes: 23 additions & 16 deletions Manuals/FDS_User_Guide/FDS_User_Guide.tex
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Expand Up @@ -2875,6 +2875,12 @@ \subsection{Solid Phase Gas Transport}

Suppose, for example, that the solid is composed of a layer of insulation on top of a layer of plastic on top of a layer of steel. The steel is impermeable. By setting \ct{LAYER_DIVIDE=2.0} to the \ct{SURF} line whose first layer is the insulation directs the vapors generated by the insulation and plastic to be driven out of the exterior surface of the insulation. Similarly, for the \ct{SURF} line that is applied to the steel, specifying \ct{LAYER_DIVIDE=0.0} would indicate that no fuel vapors are to escape the steel surface. Note that in this instance, the sum of the values of \ct{LAYER_DIVIDE} is not equal to the number of layers, but this is not a problem because the layer of steel does not generate any gases.

The solid phase output \ct{QUANTITY='PYROLYSIS DEPTH'} can check if the \ct{LAYER_DIVIDE} is being applied correctly. For example, the input line
\begin{lstlisting}
&BNDF QUANTITY='PYROLYSIS DEPTH', CELL_CENTERED=T /
\end{lstlisting}
shows the distance from the surface where the pyrolyates are directed towards that surface, as opposed to the opposite side of the solid.



\subsection{Reaction Rates}
Expand Down Expand Up @@ -11465,45 +11471,46 @@ \section{Solid Phase Output Quantities}
\ct{BACK WALL TEMPERATURE} & Section~\ref{info:BACK} & $^\circ$C & B,D \\ \hline
\ct{BLOWING CORRECTION} & Section~\ref{info:blowing} & & B,D \\ \hline
\ct{BURNING RATE} & Mass loss rate of fuel & \unit{kg/(m^2.s)} & B,D \\ \hline
\ct{CONDENSATION HEAT FLUX} & Section~\ref{info:condensation} & \unit{kW/m^2} & B,D \\ \hline
\ct{CONVECTIVE HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{CONVECTIVE HEAT FLUX GAUGE} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
{\scriptsize\tt CONVECTIVE HEAT TRANSFER REGIME} & Section \ref{info:convection} & & B,D \\ \hline
\ct{CPUA}$^2$ & Section~\ref{bucket_test_1} & \unit{kW/m^2} & B,D \\ \hline
\ct{CPUA_Z}$^1$ & Section~\ref{bucket_test_1} & \unit{kW/m^2} & B,D \\ \hline
\ct{CONDENSATION HEAT FLUX} & Section~\ref{info:condensation} & \unit{kW/m^2} & B,D \\ \hline
\ct{CONVECTIVE HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{CONVECTIVE HEAT FLUX GAUGE} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{CONVECTIVE HEAT TRANSFER REGIME} & Section \ref{info:convection} & & B,D \\ \hline
\ct{CPUA}$^2$ & Section~\ref{bucket_test_1} & \unit{kW/m^2} & B,D \\ \hline
\ct{CPUA_Z}$^1$ & Section~\ref{bucket_test_1} & \unit{kW/m^2} & B,D \\ \hline
\ct{DEPOSITION VELOCITY} & Section~\ref{info:deposition} & m/s & B,D \\ \hline
\ct{FRICTION VELOCITY} & Section~\ref{info:yplus} & m/s & B,D \\ \hline
\ct{GAUGE HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{ENTHALPY FLUX WALL} & Section~\ref{info:enthalpy_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{TOTAL HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{GAUGE HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{ENTHALPY FLUX WALL} & Section~\ref{info:enthalpy_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{TOTAL HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{EMISSIVITY} & Surface emissivity (usually constant) & & B,D \\ \hline
\ct{FIRE ARRIVAL TIME} & Section \ref{info:fire_spread_output} & \si{s} & B,D \\ \hline
\ct{FIRE RESIDENCE TIME} & Section \ref{info:fire_spread_output} & \si{s} & B,D \\ \hline
\ct{GAS DENSITY} & Gas Density near wall & \si{kg/m^3} & B,D \\ \hline
\ct{GAS TEMPERATURE} & Gas Temperature near wall & $^\circ$C & B,D \\ \hline
\ct{HEAT TRANSFER COEFFICIENT} & Section \ref{info:convection} & \si{W/(m^2.K)} & B,D \\ \hline
\ct{HRRPUA} & $\dq''$ & \unit{kW/m^2} & B,D \\ \hline
\ct{INCIDENT HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{HRRPUA} & $\dq''$ & \unit{kW/m^2} & B,D \\ \hline
\ct{INCIDENT HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{INSIDE WALL TEMPERATURE} & Section~\ref{info:DEPTH} & $^\circ$C & D,Pr \\ \hline
\ct{INSIDE WALL DEPTH} & Section~\ref{info:DEPTH} & m & D,Pr \\ \hline
\ct{MASS FLUX}$^{1,4}$ & Section~\ref{info:wallflux} & \unit{kg/(m^2.s)} & B,D \\ \hline
\ct{MASS FLUX WALL}$^1$ & Section~\ref{info:wallflux} & \unit{kg/(m^2.s)} & B,D \\ \hline
\ct{MPUA}$^2$ & Section~\ref{bucket_test_1} & kg/m$^2$ & B,D \\ \hline
\ct{MPUA_Z}$^1$ & Section~\ref{bucket_test_1} & kg/m$^2$ & B,D \\ \hline
\ct{MPUA_Z}$^1$ & Section~\ref{bucket_test_1} & kg/m$^2$ & B,D \\ \hline
\ct{NORMAL VELOCITY} & Wall normal velocity & m/s & B,D \\ \hline
\ct{NORMALIZED HEATING RATE} & Section~\ref{info:material_components} & W/g & D \\ \hline
\ct{NORMALIZED HEAT RELEASE RATE} & Section~\ref{info:material_components} & W/g & D \\ \hline
\ct{NORMALIZED MASS}$^4$ & Section~\ref{info:material_components} & & D \\ \hline
\ct{NORMALIZED MASS LOSS RATE}$^4$ & Section~\ref{info:material_components} & 1/s & D \\ \hline
\ct{OXIDATIVE HRRPUA} & Section~\ref{sec:reaction_rates} & \unit{kW/m^2} & B,D \\ \hline
\ct{PRESSURE COEFFICIENT} & Section~\ref{info:pressure_coefficient} & & B,D \\ \hline
\ct{RADIATIVE HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{RADIOMETER} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{REFERENCE_HEAT_FLUX} & Section~\ref{info:scaled_burning} & \unit{kW/m^2} & B,D \\ \hline
\ct{PYROLYSIS DEPTH} & Section~\ref{info:LAYER_DIVIDE} & m & B,D \\ \hline
\ct{RADIATIVE HEAT FLUX} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{RADIOMETER} & Section~\ref{info:heat_flux} & \unit{kW/m^2} & B,D \\ \hline
\ct{REFERENCE_HEAT_FLUX} & Section~\ref{info:scaled_burning} & \unit{kW/m^2} & B,D \\ \hline
\ct{SOLID CONDUCTIVITY}$^4$ & Section~\ref{info:DEPTH} & \si{W/(m.K)} & D,Pr \\ \hline
\ct{SOLID DENSITY}$^4$ & Section~\ref{info:DEPTH} & kg/m$^3$ & D,Pr \\ \hline
\ct{SOLID ENTHALPY}$^4$ & Section~\ref{info:DEPTH} & kJ/m$^3$ & D,Pr \\ \hline
\ct{SOLID MASS FRACTION}$^5$ & Section~\ref{info:DEPTH} & \si{kg/kg} & D,Pr \\ \hline
\ct{SOLID MASS FRACTION}$^5$ & Section~\ref{info:DEPTH} & \si{kg/kg} & D,Pr \\ \hline
\ct{SOLID SPECIFIC HEAT}$^4$ & Section~\ref{info:DEPTH} & \si{kJ/(kg.K)} & D,Pr \\ \hline
\ct{SUBSTEPS} & Section~\ref{info:solid_phase_stability} & & B,D \\ \hline
\ct{SURFACE DENSITY}$^4$ & Section~\ref{info:material_components} & kg/m$^2$ & B,D \\ \hline
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2 changes: 1 addition & 1 deletion Source/cons.f90
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Expand Up @@ -471,7 +471,7 @@ MODULE GLOBAL_CONSTANTS
REAL(EB) :: RTE_SOURCE_CORRECTION_FACTOR=1._EB !< Multiplicative factor used in correcting RTE source term
REAL(EB) :: RAD_Q_SUM=0._EB !< \f$ \sum_{ijk} \left( \chi_{\rm r} \dot{q}_{ijk}''' + \kappa_{ijk} U_{ijk} \right) V_{ijk} \f$
REAL(EB) :: KFST4_SUM=0._EB !< \f$ \sum_{ijk} 4 \kappa_{ijk} \sigma T_{ijk}^4 V_{ijk} \f$
REAL(EB) :: QR_CLIP=10._EB !< Lower bound of \f$ \chi_{\rm r} \dot{q}_{ijk}''' \f$ below which no source correction is made
REAL(EB) :: QR_CLIP=1._EB !< Lower bound of \f$ \chi_{\rm r} \dot{q}_{ijk}''' \f$ below which no source correction is made
REAL(EB) :: C_MAX=100._EB !< Maximum value of RAD_Q_SUM/KFST4_SUM
REAL(EB) :: C_MIN=0.1_EB !< Minimum value of RAD_Q_SUM/KFST4_SUM

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