Urban canopy behavior

Again the reader is referred to earlier chapters in this monograph related to air movement within urban canopy layers. Only those details related to the growth and spread of mass fires within a suburban, urban or wildland/urban interface will be discussed below. 

The authors concluded that field conditions could be reproduced by both wind tunnel and numerical models, but the numerical models were very sensitive to alternative specifications of grid resolution, wall boundary conditions, source size and turbulence 

A very comprehensive study of urban boundary layer characteristics was made by Theurer, 1992 [608] to summarize what is know about these parameters and to correlate them with building dimensions. Theurer used two parameters to describe the distribution of roughness elements  

= 2 of average building areas normal to the wind/total urban area. 

These two parameters combined with a pictorial description of the roughness pattern are sufficient to classify the roughness height, z0, and the displacement height, d, for each configuration. 

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