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FDS User Guide: Add sample level set case
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mcgratta authored Aug 4, 2023
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27 changes: 16 additions & 11 deletions Manuals/FDS_User_Guide/FDS_User_Guide.tex
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Expand Up @@ -7315,31 +7315,36 @@ \subsection{Wildfire Spread over Realistic Terrain using QGIS}
\href{https://github.com/firetools/qgis2fds}{https://github.com/firetools/qgis2fds} \\
QGIS is an open source GIS (Geographic Information System) and qgis2fds is a Python script developed by Emanuele Gissi and Ruggero Poletto that embeds topography and landuse data in an FDS input file.

A set of sample input files created by qgis2fds reside within the gitHub repository \\
\href{https://github.com/firemodels/cad}{https://github.com/firemodels/cad} \\
in the folder called {\ct Wildland\_Fire\_Spread\_Example}. There are four cases that demonstrate the four level set fire spread options over a 2~km by 2~km patch of mountainous terrain, as shown in Fig.~\ref{ridge_map}. The first image displays a satellite photograph of the area superimposed on the terrain. The second image displays the same terrain covered by 30~m square tiles, each tile representing one of thirteen different land use categories. This data is provided by LANDFIRE (Landscape Fire and Resource Management Planning Tools), a program managed by the U.S.~Forest Service and the U.S.~Department of the Interior that provides land use and elevation data for the continuental United States.

For each case, a hypothetical fire spreads from its point of origin in the lower portion of the chosen area over a ridge in the course of 24~h. The results of the four variants of the level set fire spread method are shown in Fig.~\ref{ridge_figs}.

A typical input file created with qgis2fds includes the latitude and longitude of the origin of the computational domain via {\ct ORIGIN\_LAT} and {\ct ORIGIN\_LON} on the {\ct MISC} line, in units of decimal degree. Another useful parameter is {\ct NORTH\_BEARING} (default 0$^\circ$) which indicates the direction of true north.
\begin{lstlisting}
&MISC ORIGIN_LAT=35.7207093
ORIGIN_LON=-83.5212387
NORTH_BEARING=0.
TERRAIN_IMAGE='ridge_ls_1_tex.png'
TERRAIN_IMAGE='casename.png'
LEVEL_SET_MODE=1 /
\end{lstlisting}
A set of sample input files created by qgis2fds reside within the gitHub repository \\
\href{https://github.com/firemodels/cad}{https://github.com/firemodels/cad} \\ in the folder called {\ct Wildland\_Fire\_Spread\_Example}. There are four cases that demonstrate the four level set fire spread options over a 2~km by 2~km patch of mountainous terrain, as shown in Fig.~\ref{ridge_map}. For each case, a hypothetical fire spreads from its point of origin over a ridge. Each case simulates 10~h of real time. The results of the four variants of the level set fire spread method are shown in Fig.~\ref{ridge_figs}.

\begin{figure}[!ht]
\includegraphics[width=\textwidth]{FIGURES/ridge_terrain_image.png}
\caption[Satellite image of sample terrain]{Satellite image of sample terrain.}
\begin{figure}[p]
\includegraphics[trim=0 .75in 0 .75in, clip, width=\textwidth]{FIGURES/Level_Set_Demo_1_s0000.png}
\includegraphics[trim=0 .75in 0 .75in, clip, width=\textwidth]{FIGURES/Level_Set_Demo_1_s0001.png}
\caption[Satellite and landuse images for sample wildland fire spread case]{(Top) Satellite image of a 2~km by 2~km patch of terrain. (Bottom) 30~m by 30~m tiles indicating the land use of this same area.}
\label{ridge_map}
\end{figure}

\begin{figure}[p]
\begin{tabular*}{\textwidth}{l@{\extracolsep{\fill}}r}
\includegraphics[trim=.5in 0 .5in 0, clip, height=3.0in]{FIGURES/ridge_ls_1.png} &
\includegraphics[trim=.5in 0 .5in 0, clip, height=3.0in]{FIGURES/ridge_ls_2.png} \\
\includegraphics[trim=.5in 0 .5in 0, clip, height=3.0in]{FIGURES/ridge_ls_3.png} &
\includegraphics[trim=.5in 0 .5in 0, clip, height=3.0in]{FIGURES/ridge_ls_4.png}
\includegraphics[trim=2.in 0 2.in 0, clip, height=3.5in]{FIGURES/Level_Set_Demo_1.png} &
\includegraphics[trim=2.in 0 2.in 0, clip, height=3.5in]{FIGURES/Level_Set_Demo_2.png} \\
\includegraphics[trim=2.in 0 2.in 0, clip, height=3.5in]{FIGURES/Level_Set_Demo_3.png} &
\includegraphics[trim=2.in 0 2.in 0, clip, height=3.5in]{FIGURES/Level_Set_Demo_4.png}
\end{tabular*}
\caption[Results of sample wildland fire spread simulations]{Sample wildland fire spread showing the extent of the fire front after 10~h. The plot in the upper left uses the mode 1 of the level set approach, where the wind field does not conform to the terrain but does vary in time. The plot in the upper right uses mode~2, where the terrain-conforming wind field is frozen at the time of ignition. The plot in the lower left uses mode~3, where the wind varies spatially and temporally over the entire course of the fire. The plot in the lower right uses mode~4, where the wind varies with the terrain, but also is influenced by the fire plume.}
\caption[Results of sample wildland fire spread simulations]{Sample wildland fire spread showing the extent of the fire front after 24~h. The plot in the upper left uses the mode 1 of the level set approach, where the wind field does not conform to the terrain but does vary in time. The plot in the upper right uses mode~2, where the terrain-conforming wind field is frozen at the time of ignition. The plot in the lower left uses mode~3, where the wind varies spatially and temporally over the entire course of the fire. The plot in the lower right uses mode~4, where the wind varies with the terrain, but also is influenced by the fire plume.}
\label{ridge_figs}
\end{figure}

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