caa a22 4500 47577776X CHVBK 20180406123635.0 cr unu---uuuuu 170329e20001001xx s 000 0 eng 10.1023/A:1002785830512 doi (NATIONALLICENCE)springer-10.1023/A:1002785830512 Macdonald R. Department of Mechanical Engineering, University of Waterloo, N2L 3G1, Waterloo, Ontario, Canada aut Modelling The Mean Velocity Profile In The Urban Canopy Layer [Elektronische Daten] [R. Macdonald] A simple model originally derived for meanwind speed profiles in vegetative canopy flows ismodified for application to arrays ofthree-dimensional surface obstacles (cubes), whichcould be representative of a simple urban-typesurface. It is shown that for cube arrays that arenot too densely packed, the predicted exponentialvelocity profile provides an adequate fit to thespatially averaged velocity profile (u(z))within the obstacle canopy. Application of the model to a set of wind-tunnel dataallows for the evaluation of an empirical fittingparameter called the attenuation coefficient. This isrelated to the turbulence length scale, which can befound by manipulating the results of thegradient-diffusion model used to derive the velocityprofile. The results show a reduction of theturbulence length scale with increasing obstaclepacking density. By assuming a linear transition fromthis length scale at the top of the canopy to theclassical Prandtl length scale in the overlyinginertial sublayer, an acceptable model is obtained forthe full velocity profile within simple obstaclearrays, from the ground up to the overlyingsemi-logarithmic region. Kluwer Academic Publishers, 2000 Building effects nationallicence Roughness length nationallicence Turbulence scale nationallicence Urban canopy nationallicence Urban pollution nationallicence Boundary-Layer Meteorology Kluwer Academic Publishers 97/1(2000-10-01), 25-45 0006-8314 97:1<25 2000 97 10546 https://doi.org/10.1023/A:1002785830512 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1002785830512 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Macdonald R. Department of Mechanical Engineering, University of Waterloo, N2L 3G1, Waterloo, Ontario, Canada aut NATIONALLICENCE 773 0- Boundary-Layer Meteorology Kluwer Academic Publishers 97/1(2000-10-01), 25-45 0006-8314 97:1<25 2000 97 10546 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer