Physics-based modelling of junction fires: parametric study

Background Junction fires occur when two fire fronts merge. The rate of spread (ROS) and heat release (HRR) the junction increase more quickly than that each front, this effect exacerbated by slopes. Aims Numerical modelling an interpretation their behaviour are given examining key influencing factors. Methods Twenty physics-based simulations laboratory-scale were performed for a shrub fuel bed using FIRESTAR3D, varying slope (0°–40°) angles (15°–90°). Key results Accelerative decelerative behaviours observed lower 45°, but above this, deceleration was absent. firmly related to angle evolution, which controlled flame interactions between fronts. HRR followed similar trends; maximum increased with increasing angle. Convection primary transfer mode in initial propagation phase. In no-slope cases, radiation dominant method transfer, convection dominated on Conclusions model provided great insight into behaviour. critical determining ROS Implications research helped assess effects some topographical parameters extreme fires. Situational awareness, operational predictions firefighter safety will consequently improve.