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Atmosphere 2018, 9(5), 161; https://doi.org/10.3390/atmos9050161

On Street-Canyon Flow Dynamics: Advanced Validation of LES by Time-Resolved PIV

1
Institute of Thermomechanics CAS, v.v.i., Dolejskova 1402/5, 182 00 Prague 8, Czech Republic
2
Faculty of Mathematics and Physics, Department of Atmospheric Physics, Charles University in Prague, V Holesovickach 2, 180 00 Prague 8, Czech Republic
Current address: Institute of Thermomechanics CAS, v.v.i., Dolejskova 1402/5, 182 00 Pragu 8, Czech Republic.
These authors contributed equally to this work.
*
Author to whom correspondence should be addressed.
Received: 29 January 2018 / Revised: 19 April 2018 / Accepted: 21 April 2018 / Published: 25 April 2018
(This article belongs to the Special Issue Recent Advances in Urban Ventilation Assessment and Flow Modelling)
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Abstract

The advanced statistical techniques for qualitative and quantitative validation of Large Eddy Simulation (LES) of turbulent flow within and above a two-dimensional street canyon are presented. Time-resolved data from 3D LES are compared with those obtained from time-resolved 2D Particle Image Velocimetry (PIV) measurements. We have extended a standard validation approach based solely on time-mean statistics by a novel approach based on analyses of the intermittent flow dynamics. While the standard Hit rate validation metric indicates not so good agreement between compared values of both the streamwise and vertical velocity within the canyon canopy, the Fourier, quadrant and Proper Orthogonal Decomposition (POD) analyses demonstrate very good LES prediction of highly energetic and characteristic features in the flow. Using the quadrant analysis, we demonstrated similarity between the model and the experiment with respect to the typical shape of intensive sweep and ejection events and their frequency of appearance. These findings indicate that although the mean values predicted by the LES do not meet the criteria of all the standard validation metrics, the dominant coherent structures are simulated well. View Full-Text
Keywords: wind tunnel; LES; validation; street canyon; coherent structures wind tunnel; LES; validation; street canyon; coherent structures
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Kellnerová, R.; Fuka, V.; Uruba, V.; Jurčáková, K.; Nosek, Š.; Chaloupecká, H.; Jaňour, Z. On Street-Canyon Flow Dynamics: Advanced Validation of LES by Time-Resolved PIV. Atmosphere 2018, 9, 161.

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