Study of Realistic Urban Boundary Layer Turbulence with High-Resolution Large-Eddy Simulation

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http://hdl.handle.net/10138/313901

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Auvinen , M , Boi , S , Hellsten , A , Tanhuanpaa , T & Jarvi , L 2020 , ' Study of Realistic Urban Boundary Layer Turbulence with High-Resolution Large-Eddy Simulation ' , Atmosphere , vol. 11 , no. 2 , 201 . https://doi.org/10.3390/atmos11020201

Title: Study of Realistic Urban Boundary Layer Turbulence with High-Resolution Large-Eddy Simulation
Author: Auvinen, Mikko; Boi, Simone; Hellsten, Antti; Tanhuanpaa, Topi; Jarvi, Leena
Contributor: University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)
University of Helsinki, Department of Mathematics and Statistics
University of Helsinki, Department of Forest Sciences
University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)
Date: 2020-02
Language: eng
Number of pages: 41
Belongs to series: Atmosphere
ISSN: 2073-4433
URI: http://hdl.handle.net/10138/313901
Abstract: This study examines the statistical predictability of local wind conditions in a real urban environment under realistic atmospheric boundary layer conditions by means of Large-Eddy Simulation (LES). The computational domain features a highly detailed description of a densely built coastal downtown area, which includes vegetation. A multi-scale nested LES modelling approach is utilized to achieve a setup where a fully developed boundary layer flow, which is also allowed to form and evolve very large-scale turbulent motions, becomes incident with the urban surface. Under these nonideal conditions, the local scale predictability and result sensitivity to central modelling choices are scrutinized via comparative techniques. Joint time-frequency analysis with wavelets is exploited to aid targeted filtering of the problematic large-scale motions, while concepts of information entropy and divergence are exploited to perform a deep probing comparison of local urban canopy turbulence signals. The study demonstrates the utility of wavelet analysis and information theory in urban turbulence research while emphasizing the importance of grid resolution when local scale predictability, particularly close to the pedestrian level, is sought. In densely built urban environments, the level of detail of vegetation drag modelling description is deemed most significant in the immediate vicinity of the trees.
Subject: large-eddy simulation
turbulence
urban boundary layer
urban canopy
wavelet analysis
information entropy
WIND-TUNNEL MEASUREMENTS
LARGE-SCALE MOTIONS
AMPLITUDE-MODULATION
DRAG RELATIONSHIPS
FLOW STATISTICS
LES VALIDATION
MEAN FLOW
PART II
DISPERSION
MODELS
114 Physical sciences
111 Mathematics
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