A comparison between a first-order closure model for disturbed urban canopy flows with observations for mean wind and turbulence


  1. Yee, E.
  2. Wilson, J.D.
Corporate Authors
Defence Research Establishment Suffield, Ralston ALTA (CAN);Alberta Univ, Edmonton ALTA (CAN)
Two canopy windflow models (basic model and alternative model) are described and assessed against measurements of mean wind and turbulence in a wide range of canopies (both vegetative and urban). The windflow models are based on a first-order turbulence closure for the description of both the mean wind (U) and kinetic energy of turbulence (Kappak), viz. Reynolds' equations are closed using eddy-viscosity K proportional to Lambda Kappa 1/2, where Lambda is an algebraically specified turbulence length scale. The windflow models are compared with eleven different canopy flows (aeroelastic plant canopy; corn canopy; square and staggered arrays of cubical obstacles at three different frontal area densities [0.0625, 0.16, and 0.44]; square and staggered arrays of billboard-shaped obstacles at a frontal area density of 0.16; and, the Tombstone canopy). Comparisons of model predictions with these different canopies show that the alternative windflow model gives the best overall conformance with respect to both mean flow and turbulence profiles. The basic windflow model was found to under-predict the turbulence kinetic energy within the canopy, although this underprediction does not appear to affect its reasonably good predictions of the mean wind speed and the shear stress. TRUNCATED
Turbulence Modelling in Urban Canopies;Urban Flow Modelling;CFD (Computational Fluid Dynamics);Canopy windflow modeling;Vegetative and urban canopies;Model validation
Report Number
DRES-TR-2001-058 — Technical Report
Date of publication
01 Dec 2001
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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