Dr Duncan Sutherland

My research is the application of computational fluid dynamics simulation to problems motivated by bushfires. This is a broad and rich area encompassing, buoyancy driven flows, entrainment and mixing, particle transport, contaminant modelling, and combustion modelling. 

My current research interests focus on ember storms at the Wildland Urban Interface (WUI).

During an ember storm, the embers rebound from the surface multiple times, following a process like the saltation processes observed for sand particles in aeolian processes (Dupont et al., 2013). Previous studies of ember transport have largely considered ballistic embers, which travel in single trajectories hundreds to thousands of metres from the fire front in a single ballistic arc. The damage from this kind of ember can be significant, for example, in the 2009 Black Saturday Fires in Victoria, Australia ballistic embers caused ignitions 25 km from the main fire front (Cruz et al., 2012). However, the ember transport around RUI regions, such as observed in the 2003 Canberra Fires, was not dominantly ballistic. Footage shows ember storm processes around the suburb of Duffy, where most house losses occurred, typically within 1 km of the wildland (Blanchi and Leonard, 2005, Country28 Fire-Authority, 2009, ABC-News, 2023). Despite their obvious significance, ember storms remain under research. The majority of the ember literature to date considers ballistic embers often focusing on the distance that an ember can travel (Tarifa et al., 1965, McArthur, 1967, Albini, 1983, Woycheese et al., 1998, Ellis, 2000, Koo et al., 2012, Albini et al., 2012, Martin and Hillen, 2016). Recently, Thurston et al. (2017) simulated the dispersion of embers from a fire plume using Computational Fluid Dynamics (CFD), namely, a Large Eddy Simulation (LES). While LES is routine in many fluid dynamical applications and weather forecasting, this was one of the first efforts to apply LES to ember transport. Subsequently the model for ember transport was refined by Thomas et al. (2020). Other CFD simulations such as Wadhwani et al. (2019, 2022) and Wickramasinghe et al. (2023) have studied shorter range ballistic embers interacting with flow structures that develop in downstream of forest canopies and over WUI areas.

WUIs are areas where structures and developments meet wildland. Continuous urbanisation fragments wildland areas (Gill &Williams, 1996), which creates more RUI areas. Radeloff et al. (2018) found a rapid growth of WUI areas in the United States from 1990 to 2010 that happened mostly because of new housing.

Because of the expanding population there is WUI expansion converges with the increase in extreme megafires. Studies show that the WUI regions are growing at varying rates in many countries around the world (Lampin-Maillet et al., 2010; Modugno et al., 2016). Regionally-based studies in Australia, such as (Hughes & Mercer, 2009) found that housing density inside WUI areas are increasing.

Identifying WUI areas at risk from ember storms is essential to our ultimate goal, but the first step is to establish a standardized definition and mapping methodology. A consistent approach enables comparisons across regions and improves risk assessments. We have developed and tested a new WUI definition and mapping methodology for Australia with Radeloff’s approach, demonstrating how a country-specific framework better captures the unique characteristics of Australia’s fire-prone landscapes and supports more effective bushfire risk assessment and land-use planning.