Treesearch

A computational fluid dynamics (CFD) model and a mass-consistent model were used to simulate winds on simulated fire spread over a simple, low hill. The results suggest that the CFD wind field could significantly change simulated fire spread compared to traditional uniform winds. The CFD fire spread case may match reality better because the winds used in the fire simulation were more accurate.

In southern Australia, shrubby heath vegetation together with woodlands dominated by multistemmed eucalypts (mallee) comprise areas of native vegetation with important biodiversity values. These vegetation types occur in semiarid and mediterranean climates and can experience large frequent fires. This study is investigating changes in the fuel complex with time, fuel moisture dynamics, vertical wind profile characteristics, fire propagation thresholds, rates of spread, and flame characteristics. The project is being conducted at Ngarkat Conservation Park in South Australia with data coming...

Much of the coniferous zones in the Western United States where fires were historically frequent have seen large increases in stand densities and associated forest fuels due to 20th century anthropogenic influences. This condition is partially responsible for contemporary large, uncharacteristically severe wildfires. Therefore, considerable effort is under way to reduce the potential for extreme wildfire behavior and effects, especially near communities, by manipulating canopy and surface fuels using mechanical thinning and/or prescribed burning. Treatment effectiveness, however, has been...

A useful method of modeling threats from hazards and documenting their disaster causation sequences is called “cascading threat modeling.” This type of modeling enables emergency planners to address hazard and risk assessments systematically. This paper describes a cascading threat modeling and analysis process. Wildfire and an associated postburn flash flood disaster are modeled to serve as examples of the modeling and analysis process. Models are developed for both wildfire and flash flood, and the two models are then linked at a particular threat interface. Additionally, the use of a...

Thermal radiation emission from a simulated black flame surface to a fuel bed is analyzed by a ray-tracing technique, tracking emission from points along the flame to locations along the fuel bed while accounting for absorption by environmental water vapor in the intervening medium. The Spectral Line Weighted-sum-of-gray-gases approach was adopted for treating the spectral nature of the radiation. The flame and fuel bed for the simulations are modeled two-dimensionally with the flame being one-tenth as long as the fuel bed. Flame heights of 1 and 10 m were explored, and the angle between...

An annotated bibliography for the Valles Caldera National Preserve.

The purpose of the present work is to quantify parametric uncertainty in Rothermel’s wildland fire spread model (implemented in software such as BehavePlus3 and FARSITE), which is undoubtedly among the most widely used fire spread models in the United States. This model consists of a nonlinear system of equations that relates environmental variables (input parameter groups) such as fuel type, fuel moisture, terrain, and wind to describe the fire environment. This model predicts important fire quantities (output parameters) such as the head rate of spread, spread direction, effective wind...

In an investigation of the dynamics of coupled fluid-combustion-buoyancy driven problems, an idealised model formulation is used to investigate the role of buoyancy and heat release in an evolving boundary layer, with particular emphasis on examining underlying fluid dynamics to explain observed phenomena arising in forest fire propagation. The role played by the Froude number and background ambient wind in affecting various characteristics observed in propagating fires is addressed. A simplified flow situation is modeled in which controlled amounts of volumetric heat is injected into the...

Effective mitigation of external fires on structures can be achieved flexibly, economically, and aesthetically by (1) preventing large-area ignition on structures from close proximity of burning vegetations and (2) stopping flame travel from firebrands landing on combustible building objects. In using bench-scale and mid-scale fire tests to obtain fire growth properties on common building construction and landscaping plants, a model is being developed to use fast predictive methods suitable for changing environments imposed on the parcel lot consisting of structures and ornamental plants....

On August 29, 2005, Hurricane Katrina made landfall in southern Mississippi. As the storm passed through Mississippi, it maintained hurricane force winds through the northern part of the State affecting all of the Forests. The eye of the storm passed within a few miles of the De Soto Ranger District, the Forest’s southern-most district. Much of the District received moderate to heavy damage to timber and facilities. The De Soto Ranger District had historically prescribed burned 60,000 acres per year. In the 5 years prior to hurricane Katrina, the District had increased its prescribed fire...