Scaling of Flows Over Realistic Urban Geometries: A Large-Eddy Simulation Study

A large-eddy simulation (LES) method is used to investigate the characteristics and scaling of flows over realistic urban geometries. The LES method is first validated with wind-tunnel measurements for the flow over a staggered array of cubes and the grid dependence behaviour of the LES is tested. I...

Full description

Saved in:
Bibliographic Details
Published in:Boundary-layer meteorology 2023-01, Vol.186 (1), p.125-144
Main Authors: Cheng, Wai-Chi, Yang, Ying
Format: Article
Language:English
Subjects:
Atmospheric Protection/Air Quality Control/Air Pollution
Atmospheric Sciences
Buildings
Canopies
Canopy
Cubes
Drag coefficient
Drag coefficients
Earth and Environmental Science
Earth Sciences
Flow distribution
Flow pattern
Geometry
Height
Laboratories
Large eddy simulation
Large eddy simulations
Meteorology
Methods
Mixing length
Morphology
Oceanic eddies
Plant cover
Research Article
Scaling
Shear stress
Simulation
Simulation methods
Turbulence
Urban areas
Vertical profiles
Vortices
Wind measurement
Wind tunnels
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:A large-eddy simulation (LES) method is used to investigate the characteristics and scaling of flows over realistic urban geometries. The LES method is first validated with wind-tunnel measurements for the flow over a staggered array of cubes and the grid dependence behaviour of the LES is tested. It is then applied to simulate the flows over four different realistic urban surfaces with sizes of about 1000 m  ×  500 m. After examining the overall flow patterns and turbulence characteristics, the time- and horizontally space-averaged profiles for the four cases are investigated. It is found that, in all cases, the vertical profiles of the mean streamwise velocity component can be characterized by an inflection point which can be identified as the height of the urban canopies. A new simple method is then proposed to predict this height for the realistic urban canopies based on the plan area fraction of the surfaces. By using this urban canopy height as the normalization length scale for the flows over realistic urban geometries, it is found that the vertical profiles of the dispersive stress, effective mixing length, and sectional drag coefficient show similar patterns as those of uniform height idealized urban canopies. This result would be useful for the development of urban flow parametrizations.
ISSN:0006-8314
1573-1472
DOI:10.1007/s10546-022-00749-y