Interaction between two parallel fire fronts under different wind conditions

Abstract

Wildfires often exhibit complex and dynamic behaviour arising from interactions between the fire and surrounding environment that can create a rapid fire advance and result in loss of containment and critical fire safety concerns. A series of laboratory experiments involving the interaction of two parallel fire lines on a uniform fuel bed without slope under the influence of wind is presented and discussed. The two fire lines are initially separated by a certain distance (1, 2 m) and the subsequent fire spread is described. The results show that the pyroconvective interaction between the two fire lines and ambient wind modified the rate of spread of the approaching fire lines and their associated spread characteristics, independently of the distance between them. A physical interpretation of fire evolution based on the dynamic interaction between two parallel fire lines under wind flow is proposed. We use a dimensionless physical parameter, the Froude number. The results also demonstrated the existence of a wind flow velocity between 1 and 2 m s−1, corresponding to a Froude number between 0.2 and 0.4 for which the rate of approach of the two merging fire lines is a minimum.

Field and laboratory analysis of the junction fire process in the catastrophic fire of Pedrógão Grande in June 2017

“…In these equations, we use as reference ROS values the socalled basic ROS R o , (Viegas and Pita 2004;Raposo et al 2014Raposo et al , 2018Xie et al 2014;Rodrigues et al 2019;Viegas et al 2021Viegas et al , 2022Ribeiro et al 2022Ribeiro et al , 2023) that corresponds to a linear fire spreading in the same fuel under no-wind and no-slope conditions.…”

Validation of FDS for simulating merging fires

“…Recently, Ribeiro et al (2022), carried out a set of controlled experiments to study the interaction between two parallel firelines with a working area of 8×6m 2 . The fuel bed composed of straw (Avena sativa) of height 0.07m was spread over an area of 5×4m 2 (shown in Fig.…”