Numerical-simulation of turbulent-flow and fire propagation in complex topography

A numerical model is presented for the simultaneous calculation of velocity and temperature fields, and fire propagation in mountain ridges. Turbulent fluid flow calculations are performed using the SIMPLEC procedure applied to a boundary-fitted coordinate system, while the fire rate of spread is computed using a combination of Rothermel’s fire spread model, a two-semi-ellipse formulation for fire shape, and the Dijkstra dynamic programming algorithm for fire growth simulation. To assess the influence of the ridge geometry upon isothermal flow, calculations are carried out for different height configurations. Fire computations are then made for the same configurations, and for each configuration, two types of fuel are tested. Results show a higher rate of spread for the ridge with the lower intersection angle, confirming observations that report unusually high propagation rates of fires in these topographies.