Comparison of Two and Three Dimensional Simulations of Fires at Wildland Urban Interface

Three dimensional simulations of forest fire and wind induced flows are very time consuming because the size of the computational problem becomes very large. From the economical viewpoint, the use of twodimensional simulations is an attractive alternative as means to reduce the computational cost by one or two orders of magnitude. However, the real fires and turbulent flows are never really two-dimensional, and making such simplification may introduce errors whose magnitude is not well known in advance. In this work, the effect of the 2D assumption is studied by performing a series of simulations in both two and three dimensions, and reporting the difference in the effects on structures. The results show that 2D simulations can be used for order-of-magnitude type of analysis, for which purpose they are well suited due to the small computing times. However, the differences seem to be too large for accurate predictions of the building and human response. Therefore, the critical simulations of the future analysis should be made in three dimensions.