Comprehensive Evaluation of Fast-Response, Reynolds-Averaged Navier–Stokes, and Large-Eddy Simulation Methods Against High-Spatial-Resolution Wind-Tunnel Data in Step-Down Street Canyons

Three computational fluid dynamics (CFD) methods with different levels of flow-physics modelling are comprehensively evaluated against high-spatial-resolution wind-tunnel velocity data from step-down street canyons (i.e., a short building downwind of a tall building). The first method is a semi-empi...

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Bibliographic Details
Published in:Boundary-layer meteorology Vol. 164; no. 2; pp. 217 - 247
Main Authors: Hayati, Arash Nemati, Stoll, Rob, Kim, J. J., Harman, Todd, Nelson, Matthew A., Brown, Michael J., Pardyjak, Eric R.
Format: Journal Article
Language:English
Published: Dordrecht Springer Netherlands 01.08.2017
Springer
Springer Nature B.V
Subjects:
Aspect ratio
Atmospheric Protection/Air Quality Control/Air Pollution
Atmospheric Sciences
Computational fluid dynamics
Computer applications
Computer based modeling
data collection
Earth and Environmental Science
Earth Sciences
equations
Experimental data
Flow topology
Flow velocity
Fluid dynamics
Fluid flow
Fluid mechanics
Fluid-structure interaction
geometry
GEOSCIENCES
High rise buildings
Hydrodynamics
Inflow
Large eddy simulation
Mathematical models
Meteorology
Methods
Modelling
Navier-Stokes equations
Oceanic eddies
Research Article
Resolution
Reynolds averaged Navier-Stokes method
Reynolds-averaged Navier–Stokes
Saddle points
Secondary flow
Separation
Simulation
simulation models
Spatial discrimination
Stokes law (fluid mechanics)
Street canyons
Street-canyon flow
Tall buildings
Topology
Tunnels
Turbulence (Fluid dynamics)
Updraft
Velocity
Vertical velocities
Width
wind
Wind tunnels
Flow topology
Street-canyon flow
Reynolds-averaged Navier–Stokes
Large-eddy simulation
ISSN:0006-8314, 1573-1472
Online Access:Get full text
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Summary:Three computational fluid dynamics (CFD) methods with different levels of flow-physics modelling are comprehensively evaluated against high-spatial-resolution wind-tunnel velocity data from step-down street canyons (i.e., a short building downwind of a tall building). The first method is a semi-empirical fast-response approach using the Quick Urban Industrial Complex (QUIC-URB) model. The second method solves the Reynolds-averaged Navier–Stokes (RANS) equations, and the third one utilizes a fully-coupled fluid-structure interaction large-eddy simulation (LES) model with a grid-turbulence inflow generator. Unlike typical point-by-point evaluation comparisons, here the entire two-dimensional wind-tunnel dataset is used to evaluate the dynamics of dominant flow topological features in the street canyon. Each CFD method is scrutinized for several geometric configurations by varying the downwind-to-upwind building-height ratio ( H d / H u ) and street canyon-width to building-width aspect ratio ( S  /  W ) for inflow winds perpendicular to the upwind building front face. Disparities between the numerical results and experimental data are quantified in terms of their ability to capture flow topological features for different geometric configurations. Overall, all three methods qualitatively predict the primary flow topological features, including a saddle point and a primary vortex. However, the secondary flow topological features, namely an in-canyon separation point and secondary vortices, are only well represented by the LES method despite its failure for taller downwind building cases. Misrepresentation of flow-regime transitions, exaggeration of the coherence of recirculation zones and wake fields, and overestimation of downwards vertical velocity into the canyon are the main defects in QUIC-URB, RANS and LES results, respectively. All three methods underestimate the updrafts and, surprisingly, QUIC-URB outperforms RANS for the streamwise velocity component, while RANS is superior to QUIC-URB for the vertical velocity component in the street canyon.
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USDOE
AC52-06NA25396; CBET-PDM 1134580; CBET 1512740; ACI-1053575
National Science Foundation (NSF)
LA-UR-17-27285
ISSN:0006-8314
1573-1472
DOI:10.1007/s10546-017-0245-2