Simulation of induced-wind-dominated fire on sloping terrain

Gilbert Accary (1) , Jacky Fayad (2) , François-Joseph Chatelon (2) , Nicolas Frangieh (2) , Carmen Awad (2) , Sofiane Meradji (3) , Thierry Marcelli (2) , Jean-Louis Rossi (2) , Dominique Morvan (4) , Lucile Rossi (2)

1 ULFG - Faculty of Engineering [Lebanese University]
2 SPE Université de Corse Pasquale Paoli
3 IMATH - Institut de Mathématiques de Toulon - EA 2134
4 M2P2 - Aix Marseille Université, Centrale Marseille, M2P2

Using the fully physical model FireStar3D, a numerical simulation of an eruptive fire was carried out for a grassland on a slopping terrain (30° inclination) and a 10 m-open wind speed of 2 m/s. To reproduce the behaviour of a quasi-infinite fire front, periodic conditions were considered in the fireline direction. The simulation highlights the role played by the additional wind induced by the fire (that reaches about 5.8 m/s at 10 m above ground) and its feedback action on fire behaviour. This interaction results in the transition of the fire behaviour from a plume-dominated fire to a wind-dominated fire, and this goes along with a substantial increase of the rate of spread (from 0.454 m/s to 0.714 m/s) and of the fireline heat release rate (from 4.8 MW/m to 14 MW/m). The fire regime was characterized by Byram’s convection number, based on the effective crosswind speed, that drops from 46.8 to about 3.8 once fire-induced wind takes effect on fire behaviour.

Domaines: Physique [physics]

Gilbert Accary, Jacky Fayad, François-Joseph Chatelon, Nicolas Frangieh, Carmen Awad, et al.. Simulation of induced-wind-dominated fire on sloping terrain. Advances in Forest Fire Research 2022, 1.ª Edição, Imprensa da Universidade de Coimbra, pp.375-380, 2022, ⟨10.14195/978-989-26-2298-9_59⟩. ⟨hal-03875345⟩