scholarly journals On the two ways for the computing of the fire front positions and the rate of spread

2008 ◽  
Author(s):  
K. Chetehouna ◽  
I. Zarguili ◽  
O. Séro-Guillaume ◽  
F. Giroud ◽  
C. Picard
Keyword(s):  
Rate Of Spread ◽  
Fire Front

Fine-Scale Fire Spread in Pine Straw

Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 69
Author(s):  
Daryn Sagel ◽  
Kevin Speer ◽  
Scott Pokswinski ◽  
Bryan Quaife
Keyword(s):  
Fire Spread ◽  
Small Scale ◽  
Natural Setting ◽  
Fine Scale ◽  
Prescribed Burn ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
Scale Models ◽  
Fire Front ◽  
Visible Images

Most wildland and prescribed fire spread occurs through ground fuels, and the rate of spread (RoS) in such environments is often summarized with empirical models that assume uniform environmental conditions and produce a unique RoS. On the other hand, representing the effects of local, small-scale variations of fuel and wind experienced in the field is challenging and, for landscape-scale models, impractical. Moreover, the level of uncertainty associated with characterizing RoS and flame dynamics in the presence of turbulent flow demonstrates the need for further understanding of fire dynamics at small scales in realistic settings. This work describes adapted computer vision techniques used to form fine-scale measurements of the spatially and temporally varying RoS in a natural setting. These algorithms are applied to infrared and visible images of a small-scale prescribed burn of a quasi-homogeneous pine needle bed under stationary wind conditions. A large number of distinct fire front displacements are then used statistically to analyze the fire spread. We find that the fine-scale forward RoS is characterized by an exponential distribution, suggesting a model for fire spread as a random process at this scale.

Simulation study of grass fire using a physics-based model: striving towards numerical rigour and the effect of grass height on the rate of spread

2018 ◽  
Vol 27 (12) ◽  
pp. 800 ◽  
Author(s):  
K. A. M. Moinuddin ◽  
D. Sutherland ◽  
W. Mell
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Heat Release ◽  
Bulk Density ◽  
Simulation Study ◽  
Release Rate ◽  
Rate Of Spread ◽  
Fire Front ◽  
Physics Based Simulation ◽  
Mode A

Grid-independent rate of spread results from a physics-based simulation are presented. Previously, such a numerical benchmark has been elusive owing to computational restrictions. The grid-converged results are used to systematically construct correlations between the rate of spread (RoS) and both wind speed and grass height, separately. The RoS obtained from the physics-based model is found to be linear with wind speed in the parameter range considered. When wind speed is varied, the physics-based model predicts faster RoS than the Mk III and V (McArthur) models (Noble et al. 1980) but slower than the CSIRO model (Cheney et al. 1998). When the grass height is varied keeping the bulk density constant, the fire front changes from a boundary layer flame mode to plume flame mode as the grass height increases. Once the fires are in plume mode, a higher grass height results in a larger heat release rate of the fire but a slower RoS.

Laboratory fire spread analysis using visual and infrared images

2006 ◽  
Vol 15 (2) ◽  
pp. 179 ◽  
Author(s):  
J. Ramiro Martínez-de Dios ◽  
Jorge C. André ◽  
João C. Gonçalves ◽  
Begoña Ch. Arrue ◽  
Aníbal Ollero ◽  
...  
Keyword(s):  
Graphical Model ◽  
Fire Spread ◽  
Rate Of Spread ◽  
Virtual View ◽  
Fire Front ◽  
Computer Based ◽  
Front Shape ◽  
Processing Techniques ◽  
Spread Analysis ◽  
Base Width

This paper presents an experimental method using computer-based image processing techniques of visual and infrared movies of a propagating fire front, taken from one or more cameras, to supply the time evolutions of the fire front shape and position, flame inclination angle, height, and base width. As secondary outputs, it also provides the fire front rate of spread and a 3D graphical model of the fire front that can be rendered from any virtual view. The method is automatic and non-intrusive, has space–time resolution close to continuum and can be run in real-time or deferred modes. It is demonstrated in simple laboratory experiments in beds of pine needles set upon an inclinable burn table, with point and linear ignitions, but can be extended to open field situations.

Thermodynamic structure of a grass fire plume

2010 ◽  
Vol 19 (7) ◽  
pp. 895 ◽  
Author(s):  
Craig B. Clements
Keyword(s):  
Short Duration ◽  
Combustion Zone ◽  
Rapid Heating ◽  
Ground Level ◽  
Heating Rates ◽  
Fire Plume ◽  
Thermodynamic Structure ◽  
Rate Of Spread ◽  
Fire Front ◽  
Plume Temperature

High-frequency thermocouple measurements were made during an experimental grass fire conducted during ideal weather with overcast and windy conditions. Analysis of the thermodynamic structure of the fire plume showed that a maximum plume temperature of 295.2°C was measured directly above the combustion zone. Plume heating rates were on the order of 26–45 kW m–2 and occurred in the region just above the combustion zone between 10 and 15 m above ground level and were followed by cooling of approximately –37 and –44 kW m–2. The observed cooling was caused by strong entrainment that occurred behind the fire front and plume. The rapid heating and subsequent cooling indicate that the heating caused by a fire front is limited to a small volume around the flaming front and that the rates of heat gain occur for a short duration. The short duration of plume heating is due to the fast rate of spread of the fire front and ambient wind.

Estimating error in wind speed measurements for experimental fires

2001 ◽  
Vol 31 (3) ◽  
pp. 401-409 ◽  
Author(s):  
A L Sullivan ◽  
I K Knight
Keyword(s):  
Wind Speed ◽  
Small Scale ◽  
Confidence Limits ◽  
Single Measure ◽  
Rate Of Spread ◽  
Scale Size ◽  
Fire Front ◽  
Scalar Measure ◽  
Eucalypt Forests ◽  
Measured Wind Speed

Most experimental fires, by nature, are small scale ([Formula: see text]100 m), and rate of spread measurements are taken over periods of several minutes. The aim of empirical fire modellers is to ascribe a single measure of rate of forward spread over a period to a single scalar measure of wind. The actual wind affecting the fire is unmeasurable; its value must be estimated from remote anemometry. Observation and consideration of the spatial and temporal statistics of the wind has allowed confidence limits to be placed upon the accuracy with which the measured wind reflects the wind acting on the fire front. Experimental data to verify these estimates was gathered during Project Vesta, a study into high-intensity fires in dry eucalypt forests. An equation that quantifies the accuracy of the estimate of wind affecting the fire front is given. The accuracy increases with time scale, size of the fire front, and density of anemometry. When applied to a measured wind speed taken some distance from the fire, it gives a useful estimate of the likely variation of the corresponding wind at the fire front.

scholarly journals Parameter Estimation for the Forest Fire Propagation Model

2020 ◽  
Vol 75 (1) ◽  
pp. 1-22
Author(s):  
Martin Ambroz ◽  
Karol Mikula ◽  
Marek Fraštia ◽  
Marián Marčiš
Keyword(s):  
Data Assimilation ◽  
Forest Fire ◽  
Hausdorff Distance ◽  
Small Time ◽  
Propagation Model ◽  
Model Parameters ◽  
Normal Velocity ◽  
Fire Propagation ◽  
Rate Of Spread ◽  
Fire Front

AbstractThis paper first gives a brief overview of the Lagrangian forest fire propagation model [Ambroz, M.—Balažovjech, M.—Medl’a, M.—Mikula, K.: Numerical modeling of wildland surface fire propagation by evolving surface curves, Adv. Comput. Math. 45 (2019), no. 2, 1067–1103], which we apply to grass-field areas. Then, we aim to estimate the optimal model parameters. To achieve this goal, we use data assimilation of the measured data. From the data, we are able to estimate the normal velocity of the fire front (rate of spread), dominant wind direction and selected model parameters. In the data assimilation process, we use the Hausdorff distance as well as the Mean Hausdorff distance as a criterion. Moreover, we predict the fire propagation in small time intervals.

Combustibility of a mixture of live and dead fuel components

2013 ◽  
Vol 22 (7) ◽  
pp. 992 ◽  
Author(s):  
D. X. Viegas ◽  
J. Soares ◽  
M. Almeida
Keyword(s):  
Moisture Content ◽  
Mass Fraction ◽  
Linear Models ◽  
Fuel Moisture ◽  
Fuel Component ◽  
Rate Of Spread ◽  
Fire Front ◽  
Composite Fuel ◽  
The Dead ◽  
Fuel Moisture Content

The problem of predicting the rate of spread of a linear fire front in a fuel bed composed of one live and one dead fuel component in no-slope and no-wind conditions is addressed. Two linear models based on the mass fraction of each fuel component are proposed to predict the rate of spread of a fire front as a function of the mass fraction of the dead or dry fuel component. Experimental results obtained with two different mixtures show that for each fuel mixture there is a threshold value of mass concentration of the dead fuel below which the fire front does not spread. The rate of spread results compare favourably with the proposed models. A composite fuel moisture content of the fuel bed is shown to be a good descriptor of the rate of spread of the mixture. An exponential model using composite fuel moisture content of the fuel bed is proposed to estimate the rate of spread of the mixture and a comparison is made with the concept of fuel curing that is used to characterise live fuels.

A power series formulation for two-dimensional wildfire shapes

2016 ◽  
Vol 25 (9) ◽  
pp. 970 ◽  
Author(s):  
J. E. Hilton ◽  
C. Miller ◽  
A. L. Sullivan
Keyword(s):  
Power Series ◽  
Small Scale ◽  
Two Dimensional ◽  
One Dimensional ◽  
Rate Of Spread ◽  
Mathematical Expressions ◽  
Fire Front ◽  
Small Set ◽  
Prediction Systems ◽  
The One

Computational simulations of wildfires require a model for the two-dimensional expansion of a fire perimeter. Although many expressions exist for the one-dimensional rate of spread of a fire front, there are currently no agreed mathematical expressions for the two-dimensional outward speed of a fire perimeter. Multiple two-dimensional shapes such as elliptical and oval-shaped perimeters have been observed and reported in the literature, and several studies have attempted to classify these shapes using geometric approximations. Here we show that a two-dimensional outward speed based on a power series results in a perimeter that can match many of these observed shapes. The power series is based on the dot product between the vector normal to the perimeter and a fixed wind vector. The formulation allows the evolution and shape of a fire perimeter to be expressed using a small set of scalar coefficients. The formulation is implemented using the level set method, and computed perimeters are shown to provide a good match to perimeters of small-scale experimental fires. The method could provide a framework for statistical matching of wildfire shapes or be used to improve current wildfire prediction systems.

scholarly journals Georeferencing Oblique Aerial Wildfire Photographs: An Untapped Source of Fire Behaviour Data

Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 81
Author(s):  
Henry Hart ◽  
Daniel D. B. Perrakis ◽  
Stephen W. Taylor ◽  
Christopher Bone ◽  
Claudio Bozzini
Keyword(s):  
Fire Behavior ◽  
Fire Spread ◽  
Behavior Prediction ◽  
Empirical Relationships ◽  
Rate Of Spread ◽  
Front Position ◽  
Fire Front ◽  
Initial Work ◽  
The Mean ◽  
Behaviour Data

In this study, we investigate a novel application of the photogrammetric monoplotting technique for assessing wildfires. We demonstrate the use of the software program WSL Monoplotting Tool (MPT) to georeference operational oblique aerial wildfire photographs taken during airtanker response in the early stages of fire growth. We located the position of the fire front in georeferenced pairs of photos from five fires taken 31–118 min apart, and calculated the head fire spread distance and head fire rate of spread (HROS). Our example photos were taken 0.7 to 4.7 km from fire fronts, with camera angles of incidence from −19 to −50° to image centre. Using high quality images with detailed landscape features, it is possible to identify fire front positions with high precision; in our example data, the mean 3D error was 0.533 m and the maximum 3D error for individual fire runs was less than 3 m. This resulted in a maximum HROS error due to monoplotting of only ~0.5%. We then compared HROS estimates with predictions from the Canadian Fire Behavior Prediction System, with differences mainly attributed to model error or uncertainty in weather and fuel inputs. This method can be used to obtain observations to validate fire spread models or create new empirical relationships where databases of such wildfire photos exist. Our initial work suggests that monophotogrammetry can provide reproducible estimates of fire front position, spread distance and rate of spread with high accuracy, and could potentially be used to characterize other fire features such as flame and smoke plume dimensions and spotting.

On the existence of a steady state regime for slope and wind driven fires

2004 ◽  
Vol 13 (1) ◽  
pp. 101 ◽  
Author(s):  
Domingos X. Viegas
Keyword(s):  
Steady State ◽  
Radiation Effects ◽  
Field Experiments ◽  
Blow Up ◽  
Atmospheric Conditions ◽  
Fire Propagation ◽  
Rate Of Spread ◽  
Fire Front ◽  
State Regime ◽  
Definition Of

Forest fire behaviour analysis and prediction is based on the assumption that for a given set of boundary conditions a steady-state of fire propagation exists with a well-defined rate of spread. The evolution of a fire front for linear and point ignited fires is analysed and it is shown that, even in nominally uniform and permanent conditions, the rate of spread of the head fire does not remain constant in the general case of slope- and wind-driven fires due to joint convection and radiation effects. The basic case of a linear fire front without slope and without wind is one of the few cases for which the rate of spread is well defined and remains constant. if there is slope or wind in point ignition fires, the rate of spread of the head fire tends to increase while for linear ignition fires the contrary happens. It is shown that convective effects induced by the fire for steep slope terrain can produce the so-called ‘blow-up’ effect even in the absence of any other special atmospheric conditions. Therefore the definition of rate of spread of a fire and its evaluation from laboratory and field experiments is strongly questioned.

Sign in / Sign up

Export Citation Format

Share Document