Turbulent Wildland Fire Spread by Ember Wash

Abstract

We implement an ember spotting and ember wash model within an idealized 2D coupled fire-atmosphere model. To do this, we add a stochastic transport to the background or total coupled wind field. An exponentially distributed or a normally distributed velocity anomaly added to the total wind vector represents a turbulent transport of the probability of ignition near ground by intermittent processes. These processes may include including gusts, tumbling, and near-front small-scale coherent wind eddies that trap embers and transport them forward, hence carrying the fire along the near-surface total wind field.