Flow topology and wind-driven wildfire propagation*

This work investigates the influence of wind flow patterns and topology on wildfire propagation. The Asensio wildfire model (nonlinear reactive flow) is revisited and non-dimensionalized by selecting three distinct time scales, unveiling two non-dimensional numbers, unlike the conventional approach that considers only one time scale. First, scaling analysis is performed to understand the overall wildfire behavior under the identified non-dimensional numbers. Subsequently, a wildfire transport solver is developed within a finite difference method framework, employing compact spatial schemes and an implicit-explicit Runge-Kutta time integrator. We study the characteristics of transient wildfire behavior under steady wind velocity with saddle-type fixed points, emphasizing the importance of the non-dimensional numbers, and consider unsteady wind velocity represented by the double gyre flow, examining various wind oscillation frequencies and amplitudes. This work highlights the complex interactions between wildfire dynamics and wind patterns, providing insights for a better understanding of wind-driven wildfire behavior.