The contribution of turbulent plume dynamics to long-range spotting

2017 ◽  
Vol 26 (4) ◽  
pp. 317 ◽  
Author(s):  
William Thurston ◽  
Jeffrey D. Kepert ◽  
Kevin J. Tory ◽  
Robert J. B. Fawcett
Keyword(s):  
Transport Model ◽  
Fire Spread ◽  
Substantial Impact ◽  
Landing Position ◽  
Plume Dynamics ◽  
Large Eddy ◽  
Rapid Spread ◽  
Fire Front ◽  
Turbulent Plume ◽  
Physical Realism

Spotting can start fires up to tens of kilometres ahead of the primary fire front, causing rapid spread and placing immense pressure on suppression resources. Here, we investigate the dynamics of the buoyant plume generated by the fire and its ability to transport firebrands. We couple large-eddy simulations of bushfire plumes with a firebrand transport model to assess the effects of turbulent plume dynamics on firebrand trajectories. We show that plume dynamics have a marked effect on the maximum spotting distance and determine the amount of lateral and longitudinal spread in firebrand landing position. In-plume turbulence causes much of this spread and can increase the maximum spotting distance by a factor of more than 2 over that in a plume without turbulence in our experiments. The substantial impact of plume dynamics on the spotting process implies that fire spread models should include parametrisations of turbulent plume dynamics to improve their accuracy and physical realism.

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.

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.

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.

The FireFlux II experiment: a model-guided field experiment to improve understanding of fire–atmosphere interactions and fire spread

2019 ◽  
Vol 28 (4) ◽  
pp. 308 ◽  
Author(s):  
Craig B. Clements ◽  
Adam K. Kochanski ◽  
Daisuke Seto ◽  
Braniff Davis ◽  
Christopher Camacho ◽  
...  
Keyword(s):  
Fire Spread ◽  
Model Systems ◽  
Large Set ◽  
Tall Grass ◽  
Combustion Gases ◽  
Tall Grass Prairie ◽  
Fire Front ◽  
Air Chemistry ◽  
Atmosphere Model ◽  
Behaviour Data

The FireFlux II experiment was conducted in a tall grass prairie located in south-east Texas on 30 January 2013 under a regional burn ban and high fire danger conditions. The goal of the experiment was to better understand micrometeorological aspects of fire spread. The experimental design was guided by the use of a coupled fire–atmosphere model that predicted the fire spread in advance. Preliminary results show that after ignition, a surface pressure perturbation formed and strengthened as the fire front and plume developed, causing an increase in wind velocity at the fire front. The fire-induced winds advected hot combustion gases forward and downwind of the fire front that resulted in acceleration of air through the flame front. Overall, the experiment collected a large set of micrometeorological, air chemistry and fire behaviour data that may provide a comprehensive dataset for evaluating and testing coupled fire–atmosphere model systems.

scholarly journals Meteorological Conditions Conducive to the Rapid Spread of the Deadly Wildfire in Eastern Attica, Greece

2019 ◽  
Vol 100 (11) ◽  
pp. 2137-2145 ◽  
Author(s):  
K. Lagouvardos ◽  
V. Kotroni ◽  
T. M. Giannaros ◽  
S. Dafis
Keyword(s):  
Fire Behavior ◽  
Fire Spread ◽  
High Rate ◽  
Contributing Factors ◽  
Suburban Areas ◽  
Rate Of Spread ◽  
Rapid Spread ◽  
Westerly Flow ◽  
Downslope Flow ◽  
Extreme Fire

AbstractOn 23 July 2018, Attica, Greece, was impacted by a major wildfire that took place in a wildland–urban interface area and exhibited extreme fire behavior, characterized by a very high rate of spread. One-hundred civilian fatalities were registered, establishing this wildfire as the second-deadliest weather-related natural disaster in Greece, following the heat wave of July 1987. On the day of the deadly wildfire, a very strong westerly flow was blowing for more than 10 h over Attica. Wind gusts up to 30–34 m s−1 occurred over the mountainous areas of Attica, with 20–25 m s−1 in the city of Athens and surrounding suburban areas. This strong westerly flow interacted with the local topography and acted as downslope flow over the eastern part of Attica, with temperatures rising up to 39°C and relative humidity dropping to 19% prior to the onset of the wildfire. These weather elements are widely acknowledged as the major contributing factors to extreme fire behavior. WRF-SFIRE correctly predicted the spatiotemporal distribution of the fire spread and demonstrated its utility for fire spread warning purposes.

CFD fire simulation of the Swissair Flight 111 in-flight fire – Part II: Fire spread analysis

2006 ◽  
Vol 110 (1107) ◽  
pp. 303-314 ◽  
Author(s):  
F. Jia ◽  
M. K. Patel ◽  
E. R. Galea ◽  
A. Grandison ◽  
J. Ewer
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fire Spread ◽  
Transportation Safety ◽  
Smoke Movement ◽  
Rapid Spread ◽  
Model Predictions ◽  
Computational Fluid Dynamics Cfd ◽  
Fire And Explosion ◽  
Spread Analysis

Abstract In 1998, Swissair Flight 111 (SR111) developed an in-flight fire shortly after take-off which resulted in the loss of the aircraft, a McDonnell Douglas MD-11, and all passengers and crew. The Transportation Safety Board (TSB) of Canada, Fire and Explosion Group launched a four year investigation into the incident in an attempt to understand the cause and subsequent mechanisms which lead to the rapid spread of the in-flight fire. As part of this investigation, the SMARTFIRE Computational Fluid Dynamics (CFD) software was used to predict the ‘possible’ development of the fire and associated smoke movement. In this paper the CFD fire simulations are presented and model predictions compared with key findings from the investigation. The model predictions are shown to be consistent with a number of the investigation findings associated with the early stages of the fire development. The analysis makes use of simulated pre-fire airflow conditions within the MD-11 cockpit and above ceiling region presented in an earlier publication (Part I) which was published in The Aeronautical Journal in January 2006.

scholarly journals Rapid remote sensing assessment of landscape-scale impacts from the California Camp Fire

2019 ◽  
Author(s):  
Jeffrey Chambers ◽  
Caralyn Gorman ◽  
Yanlei Feng ◽  
Margaret Torn ◽  
Jared Stapp
Keyword(s):  
Remote Sensing ◽  
Fire Spread ◽  
Early Morning ◽  
Landsat 8 ◽  
Spread Rate ◽  
Additional Information ◽  
Regional Impacts ◽  
Rapid Spread ◽  
Surrounding Landscape ◽  
The City

The Camp Fire rapidly spread across a landscape in Butte County, California, toward the city of Paradise in the early morning hours of 8 November 2018. Here we provide a set of initial tools and analyses that are useful to a variety of stakeholders, including: (1) a visualization app for GOES 16 data and the surrounding landscape showing the rapid spread of the fire from 6:37-10:47 a.m. local time; (2) processed Landsat 8 images for before, during, and after the fire, along with a tool for visualizing regional impacts; (3) a timeline of fire spread from ignition over the first four hours; and (4) a description of a potential early warning app that could make use of existing data, visualization, and analysis tools, to provide additional information for effective evacuation of communities threatened by rapidly moving wildfires. Using these tools we estimate that, over the first hour, the Camp Fire was consuming ~200 ha/minute of vegetation with a linear spread rate of 14 km over the fire’s first 25 minutes, or ~33km/hr. We briefly discuss broader use of remote sensing and geospatial analysis for fire research and risk management.

scholarly journals The relative importance of various source regions on East Asian surface ozone

2010 ◽  
Vol 10 (4) ◽  
pp. 9077-9120 ◽  
Author(s):  
T. Nagashima ◽  
T. Ohara ◽  
K. Sudo ◽  
H. Akimoto
Keyword(s):  
East Asia ◽  
Korean Peninsula ◽  
Transport Model ◽  
Surface Ozone ◽  
East Asian ◽  
Large Contribution ◽  
Chemical Transport Model ◽  
Substantial Impact ◽  
Source Regions ◽  
Surface O3

Abstract. The Source-Receptor (S-R) relationship for surface O3 in East Asia is estimated for recent years in this study utilizing the tagged tracer method with a global chemical transport model. The estimation shows the importance of intra-continental transport of O3 inside East Asia as well as the transport of O3 from distant source regions. The model well simulated the absolute concentration and seasonal variation of surface O3 in the East Asian region, and demonstrated significant seasonal difference in the origin of surface O3. More than half of surface O3 is attributable to the O3 transported from distant sources outside of East Asia in the cold season (October to March). In the warm season (April to September), most of the surface O3 is attributed to O3 created within East Asia in most areas of East Asia. The contribution of domestically-created O3 accounts for 20% of surface O3 in Japan and the Korean Peninsula, 40% in North China Plain and around 50% in the southern part of China in spring, which increase greatly in summer. The contribution of China and the Korean Peninsula to Japan are estimated at about 10% and 5%, respectively. A large contribution (20%) of China to the Korean Peninsula is also demonstrated. In the northern and southern part of China, large contribution of over 10% from East Siberia and the Indochina Peninsula are identified, respectively. The contribution of intercontinental transport increases with latitude; it is 21% in Northeast China and 13% in Japan and the Korean Peninsula in spring. As for one-hourly mean surface O3, domestically-created O3 is the main contributor in most areas of East Asia, except for the low O3 class (<30 ppbv), and accounts for more than 50% in very high O3 class (>90 ppbv). The mean relative contribution of China to central Japan was about 10% in every class, but that from the Korean Peninsula is important in all expect the low O3 class. Substantial impact of foreign sources on the exceedance of Japan's AAQS is identified in the high O3 class (60–90 ppbv) in spring.

Physical modelling of forest fire spreading through heterogeneous fuel beds

2011 ◽  
Vol 20 (5) ◽  
pp. 625 ◽  
Author(s):  
Albert Simeoni ◽  
Pierre Salinesi ◽  
Frédéric Morandini
Keyword(s):  
Field Experiments ◽  
Heterogeneous Medium ◽  
Reaction Diffusion ◽  
Physical Modelling ◽  
Fire Spread ◽  
Physical Models ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Fire Front ◽  
Fire Spreading

Vegetation cover is a heterogeneous medium composed of different kinds of fuels and non-combustible parts. Some properties of real fires arise from this heterogeneity. Creating heterogeneous fuel areas may be useful both in land management and in firefighting by reducing fire intensity and fire rate of spread. The spreading of a fire through a heterogeneous medium was studied with a two-dimensional reaction–diffusion physical model of fire spread. Randomly distributed combustible and non-combustible square elements constituted the heterogeneous fuel. Two main characteristics of the fire were directly computed by the model: the size of the zone influenced by the heat transferred from the fire front and the ignition condition of vegetation. The model was able to provide rate of fire spread, temperature distribution and energy transfers. The influence on the fire properties of the ratio between the amount of combustible elements and the total amount of elements was studied. The results provided the same critical fire behaviour as described in both percolation theory and laboratory experiments but the results were quantitatively different because the neighbourhood computed by the model varied in time and space with the geometry of the fire front. The simulations also qualitatively reproduced fire behaviour for heterogeneous fuel layers as observed in field experiments. This study shows that physical models can be used to study fire spreading through heterogeneous fuels, and some potential applications are proposed about the use of heterogeneity as a complementary tool for fuel management and firefighting.

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