Merge pull request #14761 from cxp484/FireX

FireX: Merge with firemodels/master

Author: cxp484

Manuals/FDS_Technical_Reference_Guide/FIGURES/LS_burning_rate.pdf

@@ -149,7 +149,7 @@ \subsection{Numerical Method}
 \end{equation}
 If we take the example of the face $i+\frac{1}{2}$ then
 \begin{gather}
-\phi_{\rm local} = \phi_{i+1, j}-\phi_{i, j}
+\phi_{\rm local} = \phi_{i+1, j}-\phi_{i, j} \\[6pt]
 \phi_{\rm upwind}= \begin{cases}
     \phi_{i, j}-\phi_{i-1, j} &  \quad R_x > 0 \\[6pt]
     \phi_{i+2, j}-\phi_{i+1, j} & \quad R_x < 0
@@ -200,7 +200,7 @@ \subsection{Burning Rate Model}
 \begin{figure}
     \begin{center}
         \scalebox{0.6}{\includegraphics{FIGURES/LS_burning_rate}}
-        \caption[Determination of burning rate for cell ignited in level set spread]{\label{fig:LS_burning_rate} Determination of burning rate for cell ignited in level set spread. The heat release per unit area is ramped up linearly, held at a fixed value, and ramped down linearly. The values which define this trapezoidal shape are determined for two possible scenarios. The characteristic cell depth, $D_{\rm cell}$, is greater than the fire depth, $D_{\rm fire}$, or vice versa.}
+        \caption[Determination of burning rate for cell ignited in level set spread]{\label{fig:LS_burning_rate} Determination of burning rate for cell ignited in level set spread. The heat release per unit area, $\dot{q}''$, is ramped up linearly, held at a fixed value, then ramped down linearly. The values which define this trapezoidal shape are determined for two possible scenarios: the characteristic cell depth, $D_{\rm cell}$, is greater than the fire depth, $D_{\rm fire}$, or vice versa.}
     \end{center}
 \end{figure}
 

Manuals/FDS_Technical_Reference_Guide/Wildland_Chapter.tex

@@ -359,7 +359,7 @@ MODULE GLOBAL_CONSTANTS
 REAL(EB) :: LIMITING_DT_RATIO=1.E-4_EB         !< Ratio of current to initial time step when code is stopped
 REAL(EB) :: NOISE_VELOCITY=0.005_EB            !< Velocity of random noise vectors (m/s)
 REAL(EB) :: TAU_DEFAULT=1._EB                  !< Default ramp-up time (s)
-REAL(EB) :: TAU_CHEM=1.E-10_EB                 !< Smallest reaction mixing time scale (s)
+REAL(EB) :: TAU_CHEM=1.E-5_EB                  !< Smallest reaction mixing time scale (s)
 REAL(EB) :: TAU_FLAME=1.E10_EB                 !< Largest reaction mixing time scale (s)
 REAL(EB) :: SMOKE_ALBEDO=0.3_EB                !< Parmeter used by Smokeview
 REAL(EB) :: Y_WERNER_WENGLE=11.81_EB           !< Limit of y+ in Werner-Wengle model