This work arose from the desire to develop a wildland fire simulator that could be used by firefighters in real time.
A simplified model of fire behaviour was developed within the framework of the "Fire" project capable of predicting a surface fire’s rate of spread. This model was integrated within a fire simulator:
- Simulation of non-stationary models of fire spread at valley level
A numerical diagnostic method of the state of the fire in each moment was developed. It is based on taking into account the non-stationary phenomena of extinction, acceleration and deformation of the fire front. Numerical processing takes into account the instantaneous thickness of the flame front, at a resolution of less than a meter, which poses a challenge for flame fronts extending across several kilometres. The method developed draws on a Lagrangian marker dynamic mesh of the fire front and a continuous time advancement method with adaptive time steps. The source code is available to the community through interfaces in different programming languages. This tool is accessible on the web (http://forefire.univ-corse.fr). This work led to two publications in ACL reviews (2011 Journal of Combustion, 2014 Natural Hazards and Earth System Sciences).
- Implementation of a platform for the simulation of matter
Fire Score software was developed for verifying the simulation codes of many different fires, as well as an estimation of uncertainty through an overarching approach. Developed in partnership with the INRIA, Fire Score contains methods for calculating sets of fires, using thousands of simulations of the same fire with disturbed initial conditions to determine impact probability ranges. These simulations allow us to determine the fire size potential risk (different from the combustibility risk) at land level (millions of simulations). This research was conducted within the framework of a thesis (B. Nader, 2015), co-supervised with a researcher from our UMR’s SISU Project. It led to two publications in ACL reviews (2013 International Journal of Wildland Fire, 2014 Natural Hazards and Earth System Sciences).
- Analysis of severe events using simulations of coupled fire/atmosphere interaction
The Forefire fire code was combined with the Meso-NH atmospheric model to take coupled fire/atmosphere interaction into account (partnership between the CNRM/Météo-France and the Aerology Laboratory). A parallel version of the propagation code was developed. The scientific challenges here entailed developing cascading level resolution methods, from resolution of the fire front (0.1m) to local atmosphere meshes (50m) and meso levels (2,500m). The flame front uses the Meso-NH surface wind field and returns flows (energy, mass) to the atmosphere meshes. The mega Aullène fire (3,000 hectares) was simulated, requiring 20,000 calculation hours handled by 900 processors and 24 million grid points. The parallel propagation code incorporated into Meso-NH has since been used for reanalysis of severe events. It has also been extended to lava flow issues. This research led to three publications in ACL reviews (2012 Atmospheric Environment, 2013 Proceedings of the Combustion Institute, 2014 Journal of Geophysical Research Atmospheres)
