Large-Eddy Simulation of the Atmospheric Boundary Layer

Stoll, Rob; Gibbs, Jeremy A.; Salesky, Scott T.; Anderson, William; Calaf, Marc

doi:10.1007/s10546-020-00556-3

Cited by 105 publications

(66 citation statements)

References 249 publications

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“…However, scenarios with flow alignment precisely orthogonal or parallel to the heterogeneity are likely to be the exception -not the norm -in flow systems of practical importance; alignments with some degree of obliquity are expected to be far more common (Anderson 2020). Consider, for example, atmospheric boundary layer flows encountering large-scale landscape heterogeneity at oblique angles (Bou-Zeid et al 2020;Stoll et al 2020), or hydrodynamic flows encountering panel texture variability at oblique angles. Figure 1(c) illustrates such an example of flow-heterogeneity obliquity, with 0 < θ < π/2.…”

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confidence: 99%

Flow-roughness heterogeneity: critical obliquity and salient parameters

Zheng

Anderson

2021

J. Fluid Mech.

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confidence: 99%

Flow-roughness heterogeneity: critical obliquity and salient parameters

Zheng

Anderson

2021

J. Fluid Mech.

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“…In addition, large buildings, roads systems and other infrastructure objects modify winds and turbulent dispersion shading some places or aggravating pollution in others (Gousseau et al, 2015). A growing body of literature suggests that turbulence-resolving or at least turbulence-permitting large-eddy simulation (LES) models are needed to deal with the urban pollution issues (Baklanov et al, 2017b;Brötz et al, 2014;Grimmond et al, 2020;Kurppa et al, 2018;Stoll et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Dispersion of particulate matter (PM<sub>2.5</sub>) from wood combustion for residential heating: Optimisation of mitigation actions based on large-eddy simulations

Wolf¹,

Pettersson²,

Esau³

2021

Preprint

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Abstract. Many cities in the world experience significant air pollution from residential wood combustion. Such an advection-diffusion problem as applied to geographically distributed small-scale pollution sources presently does not have a satisfactory theoretical or modelling solution. For example, statistical models do not allow for pollution accumulation in local stagnation zones – a type of phenomena that is commonly observed over complex terrain. This study applies a Parallelized Atmospheric Large-eddy simulation Model (PALM) to investigate dynamical phenomena that control variability and pathways of the atmospheric pollution emitted by wood-burning household stoves. The model PALM runs with a real spatial distribution of the pollution source and with realistic surface boundary conditions that characterize a medium-sized urban area fragmented by water bodies and hills. Such complex geography is expected to favor local air quality hazards, which makes this study of general interest. The case study here is based on winter conditions in Bergen, Norway. We investigate the turbulent diffusion of a passive scalar associated with small sized particles (PM2.5) emitted by household stoves. The study considers air pollution effects that could be observed under different policy scenarios of stove replacement; modern wood stoves emit significantly less PM2.5 than the older ones, but replacement of stoves is costly and challenging process. To solve the advection-diffusion problem, we used the PALM model at spatial resolution of 10 m in an urban-sized modelling domain of 15 km by 15 km. We found significant accumulation of near-surface pollution in the local stagnation zones. The observed concentrations were larger than concentrations due to the local PM2.5 emission, thus, indicating dominant trans-boundary contribution of pollutants for other districts. We demonstrate how the source of critical pollution can be attributed through model disaggregation of emissions from specific districts. The study reveals a decisive role of local air circulations over complex terrain that makes high-resolution modelling indispensable for adequate management of the urban air quality.This modelling study has important policy-related implications. Uneven spatial distribution of the pollutants suggests prioritizing certain limited urban districts in policy scenarios. We show that focused efforts towards stove replacement in specific areas may have dominant positive effect on the air quality in the whole municipality. The case study identifies urban districts where limited incentives would result in the strongest reduction of the population’s exposure to PM2.5.

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“…Column-based parametrization schemes for boundary layer turbulence were designed for relatively low resolution NWP simulations and assume that the horizontal grid spacing is much larger than l. This approximation is no longer valid for the simulation of the CBL with the latest NWP models [3], which operate with ∆ on the order of 1 km or less (e.g., [4][5][6]). Grid lengths of order of hundreds of metres mean that the turbulence is partially resolved, being in the regime of "coarse-grid" large eddy simulations (LES); the coarser end of this regime is sometimes called the "grey zone" or "terra incognita" [7][8][9]. Modellers need to address two key questions: (i) How physically realistic is the resolved turbulence?…”

Section: Introductionmentioning

confidence: 99%

“…Addressing these questions relies on the availability of a "truth" reference to compare against. A sufficiently high resolution LES can be used for this purpose [9]. Wurps et al [10] found grid lengths of 2.5 m, 10 m and 20 m to be sufficient to resolve the stable, neutral and CBL structures, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Resolution Dependence of Turbulent Structures in Convective Boundary Layer Simulations

2020

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Large-eddy simulations are performed using the U.K. Met Office Large Eddy Model to study the effects of resolution on turbulent structures in a convective boundary layer. A standard Smagorinsky subgrid scheme is used. As the grid length is increased, the diagnosed height of the boundary layer increases, and the horizontally- and temporally-averaged temperature near the surface and in the inversion layer increase. At the highest resolution, quadrant analysis shows that the majority of events in the lower boundary layer are associated with cold descending air, followed by warm ascending air. The largest contribution to the total heat flux is made by warm ascending air, with associated strong thermals. At lower resolutions, the contribution to the heat flux from cold descending air is increased, and that from cold ascending air is reduced in the lower boundary layer; around the inversion layer, however, the contribution from cold ascending air is increased. Calculations of the heating rate show that the differences in cold ascending air are responsible for the warm bias below the boundary layer top in the low resolution simulations. Correlation length and time scales for coherent resolved structures increase with increasing grid coarseness. The results overall suggest that differences in the simulations are due to weaker mixing between thermals and their environment at lower resolutions. Some simple numerical experiments are performed to increase the mixing in the lower resolution simulations and to investigate backscatter. Such simulations are successful at reducing the contribution of cold ascending air to the heat flux just below the inversion, although the effects in the lower boundary layer are weaker.

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Large-Eddy Simulation of the Atmospheric Boundary Layer

Cited by 105 publications

References 249 publications

Flow-roughness heterogeneity: critical obliquity and salient parameters

Flow-roughness heterogeneity: critical obliquity and salient parameters

Dispersion of particulate matter (PM<sub>2.5</sub>) from wood combustion for residential heating: Optimisation of mitigation actions based on large-eddy simulations

Resolution Dependence of Turbulent Structures in Convective Boundary Layer Simulations

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Large-Eddy Simulation of the Atmospheric Boundary Layer

Cited by 105 publications

References 249 publications

Flow-roughness heterogeneity: critical obliquity and salient parameters

Flow-roughness heterogeneity: critical obliquity and salient parameters

Dispersion of particulate matter (PM&lt;sub&gt;2.5&lt;/sub&gt;) from wood combustion for residential heating: Optimisation of mitigation actions based on large-eddy simulations

Resolution Dependence of Turbulent Structures in Convective Boundary Layer Simulations

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Dispersion of particulate matter (PM<sub>2.5</sub>) from wood combustion for residential heating: Optimisation of mitigation actions based on large-eddy simulations