A one-dimensional mean wind and turbulence model for a uniform urban canopy

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Authors
  1. Yee, E.
Corporate Authors
Defence Research Establishment Suffield, Ralston ALTA (CAN)
Abstract
A fully analytical model for the prediction of the one-dimensional mean wind speed, kinematic shear stress, turbulence kinetic energy, and velocity variances in a horizontally homogeneous canopy is described. The basis of the model centers around an analytical solution obtained by Massman and Weil (Boundary-Layer Meteorology, 91, pp. 81-107, 1999) for the turbulence kinetic energy derived from a particular form of a second-order closure model for canopy flows. Using this analytical model for the turbulence kinetic energy, it is shown how to derive analytical expressions for the wtihin canopy velocity variances using two methods: namely: (1) equilibrium partitioning whereby the velocity variances are assumed to be proportional to the turbulence kinetic energy, with the proportionality constants the same as those at the canopy top; and, (2) algebraic stress model partitioning derived from an algebraic stress model version of an existing second-order closure model for flows proposed by Launder, Reece, and Rodi (Journal of Fluid Mechanics, 68, pp. 537-566, 1975) that has been modified to include the effects on the turbulence of the extra physics arising from the interaction of the airflow with the obstacles in the array (viz., the form drag on the canopy elements, and the role of the momentum absorption over an extended volume of space on the turbulent motions within the canopy). TRUNCATED
Keywords
Atmospheric dispersion models;Distribution functions;Outdoor environments;Turbulence Modelling in Urban Canopies;Urban Flow Modelling;Atmospheric dispersion modeling
Report Number
DRES-TR-2000-071 — Technical Report
Date of publication
01 Oct 2000
Number of Pages
53
DSTKIM No
CA010806
CANDIS No
515021
Format(s):
Hardcopy;Document Image stored on Optical Disk

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