Parameterisation for a simplified short-range firebrand model from physics-based modelling

This project aims at incorporating a simplified but faithful firebrand model in Spark toolkit (taking as a representative operational model). Spotting can be classified into three categories based upon the distance travelled by the firebrands: (a) short-range spotting (up to 500-750 m), (b) medium-range spotting (1000-1500 m), and (c) long-range spotting (>5000 m). Short-range spotting is being studied extensively at Victoria University. This kind of spotting is mostly the result of firebrands blown directly ahead of the fire with little to no lofting. An experimental rig has been designed and constructed to measure firebrand landing distance and distribution which are blown with no lofting. A physics-based model, Wildland Urban Interface Fire Dynamics Simulator, WFDS, is being improved upon and validated against those sets of experiments. The experiments and modelling include both non-burning and burning firebrands.

WFDS computational simulations at laboratory scale (less than 100m) are an economical and feasible approach compared to experiments, without any of the risk and hazards associated with large-scale experimental studies. The results obtained from WFDS can be used to obtain firebrand landing, scattering and distribution for an order of magnitude to a larger scale (~1000m).  In this study, a series of WFDS simulations of large-scale scenarios of short-range ember (burning) transport will be conducted.  Required parameters for simplified firebrand dynamics for use within an operational model will be obtained via statistical analysis of firebrand behaviour and landing distributions.  This parameterisation will be applied in Spark toolkit.