Evaluation of an operational air quality model using large-eddy simulation

Grylls, Tom; Cornec, Clémence M.A. Le; Salizzoni, Pietro; Soulhac, Lionel; Stettler, Marc; Reeuwijk, Maarten van

doi:10.1016/j.aeaoa.2019.100041

Cited by 17 publications

(15 citation statements)

References 47 publications

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“…Full-scale simulations are performed with an urban version of the Dutch Large-Eddy Simulation model (Heus et al 2010) called the uDALES model (Tomas et al 2015(Tomas et al , 2016Grylls et al 2019), whose governing equations are…”

Section: Large-eddy Simulation Set-upmentioning

confidence: 99%

Steady-State Large-Eddy Simulations of Convective and Stable Urban Boundary Layers

Grylls

Suter

Reeuwijk

2020

Boundary-Layer Meteorol

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A comprehensive investigation is carried out to establish best practice guidelines for the modelling of statistically steady-state non-neutral urban boundary layers (UBL) using largeeddy simulation (LES). These steady-state simulations enable targeted studies under realistic non-neutral conditions without the complications associated with the inherently transient nature of the UBL. An extensive set of simulations of convective and stable conditions is carried out to determine which simplifications, volumetric forcings, and boundary conditions can be applied to replicate the mean and turbulent (variance and covariance) statistics of this intrinsically transient problem most faithfully. In addition, a new method is introduced in which a transient simulation can be 'frozen' into a steady state. It is found that nonneutral simulations have different requirements to their neutral counterparts. In convective conditions, capping the boundary-layer height h with the top of the modelled domain to h/5 and h/10 (which is common practice in neutral simulations) reduces the turbulent kinetic energy by as much as 61% and 44%, respectively. Consistent with the literature, we find that domain heights l z ≥ 5|L| are necessary to reproduce the convective-boundary-layer dynamics, where L is the Obukhov length. In stably stratified situations, the use of a uniform momentum forcing systematically underestimates the mechanical generation of turbulence over the urban canopy layer, and therefore leads to misrepresentations of both the inner-and outer-layer dynamics. The new 'frozen-transient' method that is able to maintain a prescribed flow state (including entrainment at the boundary-layer top) is shown to work well in both stable and convective conditions. Guidelines are provided for future studies of the capped and uncapped convective and stable UBL.

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Section: Large-eddy Simulation Set-upmentioning

confidence: 99%

Steady-State Large-Eddy Simulations of Convective and Stable Urban Boundary Layers

Grylls

Suter

Reeuwijk

2020

Boundary-Layer Meteorol

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“…Both idealized (point and line) and realistic (street network) sources can be implemented and both passive and reactive scalars can be modelled. The code supports null cycle chemistry (NO-NO 2 -O 3 reactions), and can be easily extended to more sophisticated schemes (Grylls et al, 2019;Grylls, 2020). The high spatial and temporal resolution enables analysis of e.g.…”

Section: Discussionmentioning

confidence: 99%

uDALES: large-eddy-simulation software for urban flow, dispersion, and microclimate modelling

Grylls¹,

Suter²,

Sützl³

et al. 2021

JOSS

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“… 2015 ; Grylls et al. 2019 , ][) is a high-resolution, large-eddy simulation (LES) code for simulation of the urban environment atmospheric boundary layer. LES models resolve the flow at the energetically dominant scales of turbulent motion by filtering the Navier-Stokes equations.…”

Section: Methodsmentioning

confidence: 99%

Pollutant dispersion by tall buildings: laboratory experiments and Large-Eddy Simulation

et al. 2022

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Pollutant dispersion by a tall-building cluster within a low-rise neighbourhood of Beijing is investigated using both full-scale Large-Eddy Simulation and water flume experiments at 1:2400 model-to-full scale with Particle Image Velocimetry and Planar Laser-Induced Fluorescence. The Large-Eddy Simulation and flume results of this realistic test case agree remarkably well despite differences in the inflow conditions and scale. Tall buildings have strong influence on the local flow and the development of the rooftop shear layer which dominates vertical momentum and scalar fluxes. Additional measurements using tall-buildings-only models at both 1:2400 and 1:4800 scales indicates the rooftop shear layer is insensitive to the scale. The relatively thicker incoming boundary layer affects the Reynolds stresses, the relative size of the pollutant source affects the concentration statistics and the relative laser-sheet thickness affects the spatially averaged results of the measured flow field. Low-rise buildings around the tall building cluster cause minor but non-negligible offsets in the peak magnitude and vertical location, and have a similar influence on the velocity and concentration statistics as the scale choice. These observations are generally applicable to pollutant dispersion of realistic tall building clusters in cities. The consistency between simulations and water tunnel experiments indicates the suitability of both methodologies. Graphical abstract

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Evaluation of an operational air quality model using large-eddy simulation

Cited by 17 publications

References 47 publications

Steady-State Large-Eddy Simulations of Convective and Stable Urban Boundary Layers

Steady-State Large-Eddy Simulations of Convective and Stable Urban Boundary Layers

uDALES: large-eddy-simulation software for urban flow, dispersion, and microclimate modelling

Pollutant dispersion by tall buildings: laboratory experiments and Large-Eddy Simulation

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