A simple model for wind effects of burning structures and topography on wildland–urban interface surface-fire propagation

2009 ◽  
Vol 18 (3) ◽  
pp. 290 ◽  
Author(s):  
Ronald G. Rehm ◽  
William (Ruddy) Mell
Keyword(s):  
Simple Model ◽  
Front Propagation ◽  
Ground Level ◽  
Fire Spread ◽  
Wildland Urban Interface ◽  
Fire Propagation ◽  
Interface Surface ◽  
Fire Front ◽  
Ground Slope ◽  
Structural Fires

The present paper presents a simple model to demonstrate the effect on grass-fire propagation of the winds induced by structural fires in a wildland–urban interface setting. The model combines an empirical formula for wind-driven grass-fire spread and a physics-based analytical solution to the Euler equations to determine the ground-level wind produced by the burning structure. The scaling of the wind is based on the heat release rate of the structural fire as well as other parameters. Also considered are an ambient wind and a topographical wind, assumed to be proportional to the ground slope. Data on grass and structure fires required by the model are discussed. Fire front propagation predicted by this model is illustrated by three examples: a front passing a single burning structure on flat terrain, a front passing a burning structure on a hill, and a front passing several burning structures. The model predicts that a fire front will be accelerated toward the burning structure upon approach and decelerated after passing the structure. Several burning structures multiply the effects of an individual burning structure.

A comparison of level set and marker methods for the simulation of wildland fire front propagation

2016 ◽  
Vol 25 (2) ◽  
pp. 229 ◽  
Author(s):  
Anthony S. Bova ◽  
William E. Mell ◽  
Chad M. Hoffman
Keyword(s):  
Level Set ◽  
Wildland Fire ◽  
Front Propagation ◽  
Fire Spread ◽  
Fire Dynamics ◽  
Surface Fire ◽  
Fire Dynamics Simulator ◽  
Fire Front ◽  
The Difference ◽  
Moving Front

Simulating an advancing fire front may be achieved within a Lagrangian or Eulerian framework. In the former, independently moving markers are connected to form a fire front, whereas in the latter, values representing the moving front are calculated at points within a fixed grid. Despite a mathematical equivalence between the two methods, it is not clear that both will produce the same results when implemented numerically. Here, we describe simulations of fire spread created using a level set Eulerian approach (as implemented in the wildland–urban interface fire dynamics simulator, WFDS) and a marker method (as implemented in FARSITE). Simulations of surface fire spread, in two different fuels and over domains of increasing topographical complexity, are compared to evaluate the difference in outcomes between the two models. The differences between the results of the two models are minor, especially compared with the uncertainties inherent in the modelling of fire spread.

scholarly journals LES Simulation of Wind-Driven Wildfire Interaction with Idealized Structures in the Wildland-Urban Interface

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 21
Author(s):  
Mohsen Ghaderi ◽  
Maryam Ghodrat ◽  
Jason J. Sharples
Keyword(s):  
Numerical Data ◽  
Fire Spread ◽  
Fire Effects ◽  
Combustion Model ◽  
Wildland Urban Interface ◽  
Building Model ◽  
Eddy Simulation ◽  
Fire Front ◽  
Physical Phenomena ◽  
The Impact

This paper presents a numerical investigation of the impact of a wind-driven surface fire, comparable to a large wildfire, on an obstacle located downstream of the fire source. The numerical modelling was conducted using FireFOAM, a coupled fire-atmosphere model underpinned by a large eddy simulation (LES) solver, which is based on the Eddy Dissipation Concept (EDC) combustion model and implemented in the OpenFOAM platform (an open source CFD tool). The numerical data were validated using the aerodynamic measurements of a full-scale building model in the absence of fire effects. The results highlighted the physical phenomena contributing to the fire spread pattern and its thermal impact on the building. In addition, frequency analysis of the surface temperature fluctuations ahead of the fire front showed that the presence of a building influences the growth and formation of buoyant instabilities, which directly affect the behaviour of the fire’s plume. The coupled fire-atmosphere modelling presented here constitutes a fundamental step towards better understanding the behaviour and potential impacts of large wind-driven wildland fires in wildland-urban interface (WUI) areas.

Efficient simulation of wildfire spread on an irregular grid

2008 ◽  
Vol 17 (5) ◽  
pp. 614 ◽  
Author(s):  
Paul Johnston ◽  
Joel Kelso ◽  
George J. Milne
Keyword(s):  
Discrete Event ◽  
Front Propagation ◽  
Fire Spread ◽  
Computational Method ◽  
Shape Distortion ◽  
Irregular Grid ◽  
Simulation Techniques ◽  
Fire Front ◽  
Wildfire Simulation ◽  
Propagation Methods

A cell-based wildfire simulator that uses an irregular grid is presented. Cell-based methods are simpler to implement than fire front propagation methods but have traditionally been plagued by fire shape distortion caused by the fire only being able to travel in certain directions. Using an irregular grid randomises the error introduced by the grid, so that the shape of simulated fire spread is independent of the direction of the wind with respect to the underlying grid. The cell-based fire spread simulator is implemented using discrete event simulation, which is a much more efficient computational method than conventional wildfire simulation techniques because computing resources are not used in repeatedly computing small updates to parts of the fire whose dynamics change infrequently, namely those areas of a fire that move slowly. The resulting simulator is comparable in accuracy with traditional fire front propagation schemes but is much faster and can therefore be used as an engine for fire simulation applications that require large numbers of simulations, such as in the role of a risk analysis engine.

scholarly journals Ignition Vulnerabilities of Combustibles around Houses to Firebrand Showers: Further Comparison of Experiments

2021 ◽  
Vol 13 (4) ◽  
pp. 2136
Author(s):  
Sayaka Suzuki ◽  
Samuel L. Manzello
Keyword(s):  
Experimental Data ◽  
Thermal Radiation ◽  
Driving Force ◽  
Fire Spread ◽  
Significant Problem ◽  
Next Generation ◽  
Similar Time ◽  
Comparison Of Experiments ◽  
Fire Front ◽  
Wui Fires

Wildland fires and wildland urban-interface (WUI) fires have become a significant problem in recent years. The mechanisms of home ignition in WUI fires are direct flame contact, thermal radiation, and firebrand attack. Out of these three fire spread factors, firebrands are considered to be a main driving force for rapid fire spread as firebrands can fly far from the fire front and ignite structures. The limited experimental data on firebrand showers limits the ability to design the next generation of communities to resist WUI fires to these types of exposures. The objective of this paper is to summarize, compare, and reconsider the results from previous experiments, to provide new data and insights to prevent home losses from firebrands in WUI fires. Comparison of different combustible materials around homes revealed that wood decking assemblies may be ignited within similar time to mulch under certain conditions.

scholarly journals Reconstruction of Grenfell Tower fire. Part 3—Numerical simulation of the Grenfell Tower disaster: Contribution to the understanding of the fire propagation and behaviour during the vertical fire spread

2019 ◽  
Vol 44 (1) ◽  
pp. 35-57 ◽  
Author(s):  
Eric Guillaume ◽  
Virginie Dréan ◽  
Bertrand Girardin ◽  
Faiz Benameur ◽  
Maxime Koohkan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fire Spread ◽  
Fire Propagation

scholarly journals Drone Swarms in Fire Suppression Activities: A Conceptual Framework

Drones ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 17
Author(s):  
Elena Ausonio ◽  
Patrizia Bagnerini ◽  
Marco Ghio
Keyword(s):  
Technological Development ◽  
Fire Suppression ◽  
Water Flow Rate ◽  
Cellular Automata Model ◽  
Fire Propagation ◽  
Active Fire ◽  
Fire Front ◽  
Main Factors ◽  
Mediterranean Scrub ◽  
In Fire

The recent huge technological development of unmanned aerial Vehicles (UAVs) can provide breakthrough means of fighting wildland fires. We propose an innovative forest firefighting system based on the use of a swarm of hundreds of UAVs able to generate a continuous flow of extinguishing liquid on the fire front, simulating the effect of rain. Automatic battery replacement and extinguishing liquid refill ensure the continuity of the action. We illustrate the validity of the approach in Mediterranean scrub first computing the critical water flow rate according to the main factors involved in the evolution of a fire, then estimating the number of linear meters of active fire front that can be extinguished depending on the number of drones available and the amount of extinguishing fluid carried. A fire propagation cellular automata model is also employed to study the evolution of the fire. Simulation results suggest that the proposed system can provide the flow of water required to fight low-intensity and limited extent fires or to support current forest firefighting techniques.

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.

scholarly journals Numerical Investigations on the Propagation of Fire in a Railway Carriage

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4999
Author(s):  
Matthew Craig ◽  
Taimoor Asim
Keyword(s):  
Fire Spread ◽  
Ignition Energy ◽  
Fire Dynamics ◽  
Fire Propagation ◽  
Average Temperature ◽  
Smoke Density ◽  
Smoke Layer ◽  
Most Significant Change ◽  
Computational Fluid Dynamics Cfd ◽  
Safety Guidelines

In this study, advanced Computational Fluid Dynamics (CFD)-based numerical simulations have been performed in order to analyse fire propagation in a standard railway compartment. A Fire Dynamics Simulator (FDS) has been employed to mimic real world scenarios associated with fire propagation within railway carriages in order to develop safety guidelines for railway passengers. Comprehensive parametric investigations on the effects of ignition location, intensity and cabin upholstery have been carried out. It has been observed that a fire occurring near the exits of the carriage results in a lower smoke layer height, due to the local carriage geometry, than an identical fire igniting at the center of the carriage. This in turn causes the smoke density along the aisleway to vary by around 30%. Reducing the ignition energy by half has been found to restrict combustion, thus reducing smoke density and carbon exhaust gases, reducing the average temperature from 170 °C to 110 °C. Changing the material lining of the seating has been found to cause the most significant change in output parameters, despite its relative insignificance in bulk mass. A polyester sample produces a peak carbon monoxide concentration of 7500 ppm, which is 27× greater compared with nylon. This difference has been found to be due to the fire spread and propagation between fuels, signifying the polyester’s unsuitability for use in railway carriages.

Ignition of mulch and grasses by firebrands in wildland - urban interface fires

2006 ◽  
Vol 15 (3) ◽  
pp. 427 ◽  
Author(s):  
Samuel L. Manzello ◽  
Thomas G. Cleary ◽  
John R. Shields ◽  
Jiann C. Yang
Keyword(s):  
Moisture Content ◽  
Air Flow ◽  
Fire Spread ◽  
Test Cell ◽  
Wildland Urban Interface ◽  
Size Number ◽  
Ignition Regime ◽  
Pine Straw ◽  
Ignition Propensity ◽  
Wui Fires

Firebrands or embers are produced as trees and structures burn in wildland–urban interface (WUI) fires. It is believed that firebrand showers created in WUI fires may ignite vegetation and mulch located near homes and structures. This, in turn, may lead to ignition of homes and structures due to burning vegetation and mulch. Understanding the ignition events that are due to firebrands is important to mitigate fire spread in communities. To assess the ignition propensity of such materials, simulated firebrands of uniform geometry, but in two different sizes, were allowed to impinge on fuel beds of shredded hardwood mulch, pine straw mulch, and cut grass. The moisture content of these materials was varied. Firebrands were suspended and ignited within the test cell of the Fire Emulator/Detector Evaluator (FE/DE) apparatus. The FE/DE was used to investigate the influence of an air flow on the ignition propensity of a fuel bed. Ignition regime maps were generated for each material tested as a function of impacting firebrand size, number of deposited firebrands, air flow, and material moisture content.

scholarly journals Modelling of wildland-urban interface fire spread with the heterogeneous cellular automata model

2021 ◽  
Vol 135 ◽  
pp. 104895
Author(s):  
Wenyu Jiang ◽  
Fei Wang ◽  
Linghang Fang ◽  
Xiaocui Zheng ◽  
Xiaohui Qiao ◽  
...  
Keyword(s):  
Cellular Automata ◽  
Fire Spread ◽  
Wildland Urban Interface ◽  
Cellular Automata Model
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