You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
Copy file name to clipboardExpand all lines: Manuals/FDS_User_Guide/FDS_User_Guide.tex
+3Lines changed: 3 additions & 0 deletions
Original file line number
Diff line number
Diff line change
@@ -11320,6 +11320,8 @@ \subsection{Fire spread over a surface}
11320
11320
\label{info:fire_spread_output}
11321
11321
In some cases it can be useful to output timings related to the spread of fire over a surface. For example, when modeling wildland fires the shape and spread of the fire front can be very important. For this reason, two specialized output quantities are available as boundary files (Sec.~\ref{info:BNDF}) or as measurements from devices places on a solid boundary (Sec.~\ref{info:DEVC2}). These are \ct{FIRE ARRIVAL TIME} and \ct{FIRE RESIDENCE TIME}. The \ct{FIRE ARRIVAL TIME} quantity outputs the time at which the gas-phase cell adjacent to the solid exceeds a threshold for heat release rate per volume (\ct{HRRPUV}) and the \ct{FIRE RESIDENCE TIME} gives the cummulative time over which the threshold is exceeded during the simulation. The chosen threshold is the same as used by smokeview for rendering \ct{HRRPUV}, as described in Sec.~\ref{info:SMOKE3D}. In the case of a level set simulation (Sec.~\ref{info:level_set}), the \ct{FIRE ARRIVAL TIME} can be computed directly from the level set value and the \ct{FIRE RESIDENCE TIME} comes from the spread-rate adjusted burning duration of the fuel, as described in Sec.~\ref{level_set_fuel_model_1}. These two quantities are cummulatively populated over time such that a full picture of the fire spread can be obtained from relatively infrequent outputs - theoretically only one snapshot at the end of the simulation is required.
11322
11322
11323
+
For level set simulations another output is availble, called \ct{LS SPREAD RATE}. This output stores the magnitude of the local spread rate calculated as the fire reaches a given point along the surface. The dependence on slope and local wind is related to the mode of level set which is activated (Sec.~\ref{info:level_set}).
0 commit comments