CFD modelling of WUI fire behaviour in historical fire cases according to different fuel management scenarios

Abstract Background : In most Wildland-Urban Interface (WUI) fires, damage to building results from poor surrounding vegetation management. No simulation had been conducted yet on historical WUI fires with CFD modelling. Aims : It was interesting to check the feasibility of this modelling in simulating past fire cases in different scenarios of vegetation management and fire propagation. Methods : We studied three cases of WUI dwellings surrounded by gardens (submitted to the French regulation on fuel reduction) adjacent to forest that were affected by a past fire. The 3D fire propagation was assessed using the Fire Dynamic Simulator model (FDS) and taking into account accurate fire environment (fine vegetation distribution, terrain, etc.). Key results : Results showed that, in the current model state, the brush-clearing mitigated the fire intensity and propagation and damage to the ornamental vegetation. However, it highlighted sometimes that this measure could be strengthened when the effects of topography and wind were combined. Conclusions : FDS modelling at WUI scale, using an accurate vegetation distribution proved to be functionally satisfactory, exhibiting realistic fire behaviour. Implications : Once validated, this modelling will ultimately help to assess when fuel reduction is efficient in fire mitigation and to pinpoint possible limitations