Wind in a Natural and Artificial Wildland Fire Fuel Bed

Yana Bebieva,Liam White,Kevin Speer,Gabrielle Mayans,Robert Smith,Bryan Quaife

doi:10.3390/fire4020030

Abstract

Fuel beds represent the layer of fuel that typically supports continuous combustion and wildland fire spread. We examine how wind propagates through and above loose and packed pine needle beds and artificial 3D-printed fuel beds in a wind tunnel. Vertical profiles of horizontal velocities are measured for three artificial fuel beds with prescribed porosities and two types of fuel beds made with long-leaf pine needles. The dependence of the mean velocity within the fuel bed with respect to the ambient velocity is linked to the porosity. Experimental results show significant structure to the vertical profile of mean flow within the bed, and suggest that small-scale sweeps and ejections play a role in this system redistributing momentum similar to larger-scale canopy flows.

Highlights

The degree of fire behavior predictability in numerical models strongly depends on the correct representation of the surface wind and its interaction with surface or ground fuels
We examine the vertical structure of horizontal wind within the lowest part of the atmospheric boundary layer—the fuel layer, which typically consists of pine needles, branches, and leaves [1] (Figure 1)
We present experimental results focusing on the properties of mean streamwise velocity profiles and fluctuations as a function of different fuel beds

Summary

Introduction

The degree of fire behavior predictability in numerical models strongly depends on the correct representation of the surface wind and its interaction with surface or ground fuels. We examine the vertical structure of horizontal wind within the lowest part of the atmospheric boundary layer—the fuel layer, which typically consists of pine needles, branches, and leaves [1] (Figure 1). For combustion, oxygen inflow is critical and is controlled by the eddy dynamics. These dynamics depend, in turn, on the vertical structure of the mean velocity field within and above the surface layer

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