D. Sutherland

• PhD Applied Mathematics
• Lecturer at UNSW Sydney

Variations in solute concentration in a fluid is a common occurrence in natural scenarios, including salinity differences in the ocean and smoke propagation in bushfires. Flow in such scenarios may be induced with placement of a heavy fluid into a lighter ambient fluid, the ambient density may itself vary with height. In this study, a system of sha...

Consider the propagation of a gravity current released from a cylindrical lock of radius ! and height , propagating into a linearly stratified ambient with stratification strength (). Direct numerical simulations (DNSs) are performed with a full-depth release on a horizontal plane at a high Reynolds number, using the Boussinesq approximation. The r...

The effects from variations in frontal surface area on planar three-dimensional, full-depth release, lock exchange Boussinesq gravity currents have presently been considered. A sinusoidal variation in the spanwise is imposed on the frontal surface with wavenumbers ranging between ky = 0 and 33.5. In the case of no sinusoidal variation, the current...

Merging fire is a complex dynamic behaviour of wildfire that plays a critical role in the growth and propagation of wildfires. There is empirical evidence of such behaviour significantly altering the rate of fire spread and fire behaviour. Despite such evidence, the present operation models still lack correlations to account for merging behaviour....

Direct numerical simulations (DNSs) of three-dimensional cylindrical release gravity currents in a linearly stratified ambient are presented. The simulations cover a range of stratification strengths $0< S\leq 0.8$ (where $S=(\rho _b^*-\rho _0^*)/(\rho _c^*-\rho _0^*), \rho _b^*, \rho _0^*$ and $\rho _c^*$ are the dimensional density at the bottom...

Driving wind and slope of terrain can increase the rate of surface fire propagation. Previous physical modelling under higher driving wind (3–12.5 m/s) on slopes (Innocent et al., IJWF, 2023, 32(4), pp. 496–512 and 513–530) demonstrated that the averaged rate of fire spread (RoS) varied from that of empirical models. This study investigates the pot...

Background Wildfire often shows complex dynamic behaviour due to the inherent nature of ambient conditions, vegetation and ignition patterns. Merging fire is one such dynamic behaviour that plays a critical role in the safety of structures and firefighters. Aim & method The aim of this study was to develop better insight and understanding of the i...

Background Junction fires occur when two fire fronts merge. The rate of spread (ROS) and heat release rate (HRR) of the junction increase more quickly than that of each fire front, this effect exacerbated by slopes. Aims Numerical modelling of junction fires and an interpretation of their behaviour are given examining the key influencing factors....

Homogeneous vegetation is widely used in wildland fire behaviour models, although real vegetation is heterogeneous in nature and composed of different kinds of fuels and non-combustible parts. Many features of fires can arise from this heterogeneity. For land management and firefighting, creating heterogeneous fuel areas may be useful to reduce fir...

This study focuses on physics-based modelling of grassfire behaviour over flat and sloped terrains through a set of field-scale simulations performed using the Wildland–urban Interface Fire Dynamics Simulator (WFDS), with varying wind speeds (12.5, 6 and 3 m s⁻¹) and slope angles (−30° to +30°). To ensure the accuracy of this Large Eddy Simulation...

The interaction of wind and fire on a sloped terrain is always complex owing to the mechanisms of heat transfer and flame dynamics. Heating of unburned vegetation by attached flames may increase the rate of spread. The relative intensities of convective and radiative heat fluxes may change fire behaviour significantly. This paper presents a detaile...

Firebrands (often called embers) increase the propagation rate of wildfires and often cause the ignition and destruction of houses. Predicting the motion of firebrands and the ignition of new fires is therefore of significant interest to fire authorities. Numerical models have the potential to accurately predict firebrand transport. The present stu...

Firebrands (often called embers) increase the propagation rate of wildfires and often cause the ignition and destruction of houses. Predicting the motion of firebrands and the ignition of new fires is therefore of significant interest to fire authorities. Numerical models have the potential to accurately predict firebrand transport. The present stu...

O período entre 2018 e 2022 mostrou-nos que o problema dos incêndios à escala global não está a diminuir, antes pelo contrário. Parece que as consequências das alterações climáticas já estão a afectar a ocorrência de incêndios florestais em várias partes do Mundo, de uma forma que só esperaríamos que acontecesse vários anos mais tarde. Em muitos pa...

O período entre 2018 e 2022 mostrou-nos que o problema dos incêndios à escala global não está a diminuir, antes pelo contrário. Parece que as consequências das alterações climáticas já estão a afectar a ocorrência de incêndios florestais em várias partes do Mundo, de uma forma que só esperaríamos que acontecesse vários anos mais tarde. Em muitos pa...

Firebrands play a crucial role in increasing the severity of wildfires by driving fire growth, damaging structures, and starting new fires. Predicting the transport of firebrands and their propensity to ignite new fires is of significant interest to fire communities. Developing an operational firebrand transport sub-model from the field studies is...

Wildfire behaviour prediction is a complex and challenging endeavour that incorporates information relating to various factors such as vegetation, local and ambient weather conditions, and topography within a particular modelling framework. Often, a single model cannot provide a complete description of the phenomenon due to significant differences...

Relative humidity of air is directly related to fuel moisture. Fuel moisture is often considered as the index of flammability in the context of bushfire. Variation of relative humidity and fuel moisture is considered to have a significant effect on the rate of spread of grassfire propagation and fire intensity. In this study, four sets of grassfire...

The behavior of a grassland fire propagating downstream of a forest canopy has been simulated numerically using the fully physics-based wildfire model FIRESTAR3D. This configuration reproduces quite accurately the situation encountered when a wildfire spreads from a forest to an open grassland, as can be the case in a fuel break or a clearing, or d...

The view-factor model essentially estimates how much of the fire is 'seen' by the structure. The example simulation shown in Figure 1 has a schematic of the view-factor model superimposed upon it. AS 3959 assumes (among other idealisations) a straight-line fire of 100 m width with a constant flame temperature of 1090 K, and seeks to maximize the vi...

Predicting the rate of spread (RoS) and intensity of bushfires are essential for emergency and disaster management organisations. Factors, such as localised topography, weather conditions, vegetation, and terrain have varying range of influences on RoS which makes the prediction highly complex. Currently, RoS predictions are achieved by implementin...

Wildland fires occur naturally in several parts of Australia and around the world and result in loss of life and property. The need to control and manage such fires opens up an extensive domain for research. This has lead to the development of several numerical models to simulate these fires and provide mitigation plans. Physics-based models act as...

The atmospheric boundary layer flow dynamics over a vegetated hill, even though neutrally stratified, is far more complex comparing to the flow over flat ground. There is a need to study the dynamics of this flow in detail for the many environmental applications, such as forest management, wind energy monitoring for potential location of wind turbi...

Australian building standard AS 3959 provides mandatory requirements for the construction of buildings in bushfire prone areas in order to improve the resilience of the building to radiant heat, flame contact, burning embers, and a combination of these three bushfire attack forms. The construction requirements are standardized based on the bushfire...

Australian building standard AS 3959 provides mandatory requirements for the construction of buildings in bushfire prone areas in order to improve the resilience of the building to radiant heat, flame contact, burning embers, and a combination of these three bushfire attack forms. The construction requirements are standardized based on the bushfire...

Wildland fires can take different forms such as surface fire or an elevated crown fire or combination of both. Crown fires are normally originated from surface fires spreading either along the bark of the tree trunks or direct flame contact to low branches with leaves and needles. In the past, surface fire (grassfire) spread simulations were conduc...

The effect of ignition protocol on the development of grassfires is investigated using physics-based simulation. Simulation allows measurement of the forward rate of spread of a fire as a function of time at high temporal resolution. Two ignition protocols are considered: the inward ignition protocol, where the ignition proceeds in a straight line...

Wind is one of the most important environmental variables that affects the wildland fire spread and intensity. Modelling wind in physics-based models such as Fire Dynamics Simulator (FDS) has been shown to reproduce promising results. There are various methods available to generate wind field in FDS. The current paper deals with finding out a bette...

Large eddy simulations of flow over heterogeneous forest canopies are performed. Each simulated forest consists of equal-sized strip canopies which alternate in the streamwise direction between sparse and dense leaf area density. Quadrant analysis is then used to investigate the eddy fluxes near the top of the forest with an eye towards developing...

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 ob...

The propagation of fire inside a typical forest canopy is heavily dependent on the amount of oxygen present during the fire propagation, fire intensity, and ignitability of surface fuels which is generally composed of forest litter, shrubs, etc. In eucalyptus vegetation the forest litter predominantly contains eucalyptus leaves, twigs, and bark. Th...

Rapid expansion of urbanization has led to the increased vulnerability of infrastructures to bushfires and wildfires. Australian, bridge inspection manuals recommend a level 3 type of investigation as a post bushfire bridge evaluation. Fire/structure interactions are dependent on fuel quantity, geometry, fuel characteristics, ambient conditions and...

Models for the thermal degradation (or pyrolysis) of solid fuel are fundamental to the physics-based simulation of grassfires. The pyrolysis process affects the combustion process and therefore the simulated flame, which defines the fire front. There are two competing models: a simple linear parameterisation and a non-linear Arrhenius model. The pr...

Wildland fires or bushfires can be a surface fire such as a grassfire or an elevated crown fire. Crown fires are often supposed to originate from surface fires spreading either along the bark of the tree trunks or direct flame contact to low branches with leaves and needles. In a previous study, surface fire (grassfire) spread simulation was succes...

Simulations of a fire entering, propagating under and leaving a tree canopy are conducted using FDS [1], a physics-based model.

Wildfires are an integral feature of the Australian continent. To estimate the rate of spread of wildfires using computational models it is important to know the kinetic parameters of the materials that constitute the fuel load in forests. These kinetic parameters are utilised in pyrolysis and combustion sub-models of a computational model. In the...

Firebrands are a harbinger of damage to infrastructure; their effects cause a particularly important threat to people living within the wildland-urban-interface. Short-range firebrands travel with the wind with little or no lofting, and cause spotfires. In this work, the design of a novel firebrand generator prototype is discussed to achieve a unif...

Operational fire models rely on wind reduction factors to relate the standard meteorological measured or forecast wind speed to the flame-height wind speeds within a tree canopy. We investigate the wind flow over idealised rectangular tree canopies using Large Eddy Simulation (LES) with an eye towards developing a model of the wind reduction factor...

The present poster discusses the effect of shape on the transport of passive firebrand particles

The present poster discussed the design of a new type of firebrand generator to generate a uniform shower of firebrands for controlled experiment and simulation

The problem of a dipole incident normally on a rigid boundary, for moderate to large Reynolds numbers, has recently been treated numerically using a volume penalisation method by Nguyen van yen, Farge, and Schneider [Phys. Rev. Lett. 106, 184502 (2011)]. Their results indicate that energy dissipating structures persist in the inviscid limit. They f...

The presence of a canopy reduces the local wind speed, resulting in a slower rate of spread of a wildfire than in the open