Dispersion in an array of buildings in stable and convective atmospheric conditions

Marucci, Davide; Carpentieri, Matteo

doi:10.1016/j.atmosenv.2019.117100

Cited by 28 publications

(14 citation statements)

References 26 publications

(57 reference statements)

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“…Measurements were performed inside and above the canopy, as well as measurements of the undisturbed approaching flow, to evaluate the effect of the presence of the model. Dispersion measurements were also performed simultaneously and results are reported elsewhere (Marucci and Carpentieri, 2019a).…”

Section: Resultsmentioning

confidence: 99%

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Stable and convective boundary-layer flows in an urban array

Marucci

Carpentieri

2020

Journal of Wind Engineering and Industrial Aerodynamics

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In this paper non-neutral approaching flows were employed in a meteorological wind tunnel on a regular urban-like array of rectangular buildings. As far as stable stratification is concerned, results on the flow above and inside the canopy show a clear reduction of the Reynolds stresses and an increment of the Monin-Obukhov length up to 80%. The roughness length and displacement height were also affected, with a reduction up to 35% for the former and an increment up to 12% for the latter. A clear reduction of the turbulence within the canopy was observed. In the convective stratification cases, the friction velocity appears increased by both the effect of roughness and unstable stratification. The increased roughness causes a reduction in the surface stratification, reflected in an increase of the Monin-Obukhov length, which is double over the array compared to the approaching flow. The effect on the aerodynamic roughness length and displacement height are specular to the SBL case, an increase up to 50% of the former and a reduction of the same amount for the latter.

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Section: Resultsmentioning

confidence: 99%

“…This paper deals mainly with the modifications in the flow, turbulence and temperature fields introduced by a non-neutral stratification on an urban array. Dispersion measurements were also carried out, but the results will be reported elsewhere (Marucci and Carpentieri, 2019a) 2. Methodology…”

Section: Introductionmentioning

confidence: 99%

Stable and convective boundary-layer flows in an urban array

Marucci

Carpentieri

2020

Journal of Wind Engineering and Industrial Aerodynamics

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“…With this approach, they provided a set of measurements of all dispersion components, meandering, relative dispersion, and total dispersion, and discussed the (increased) centreline decay of concentration fluctuation intensity with respect to the neutral non-buoyant case, as reported by Fackrell and Robins (1982a). Finally, Marucci and Carpentieri (2020) recently investigated the effect of stable and convective atmospheric conditions on the mean and variance of the concentration within and above an obstacle array. As far as we are aware, no other experiments have so far investigated the concentration fluctuations within stably stratified flows.…”

Section: Non-neutral Flowsmentioning

confidence: 99%

“…Other recent works on urban-like geometries include the already cited study of Marucci and Carpentieri (2020) and that of Di Bernardino et al (2019) who, however, mainly focused on the determination of the turbulent Schmidt number rather than the concentration fluctuations.…”

Section: Urban Mock-upmentioning

confidence: 99%

Concentration Fluctuations from Localized Atmospheric Releases

Cassiani

Bertagni

Marro

et al. 2020

Boundary-Layer Meteorol

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We review the efforts made by the scientific community in more than seventy years to elucidate the behaviour of concentration fluctuations arising from localized atmospheric releases of dynamically passive and non-reactive scalars. Concentration fluctuations are relevant in many fields including the evaluation of toxicity, flammability, and odour nuisance. Characterizing concentration fluctuations requires not just the mean concentration but also at least the variance of the concentration in the location of interest. However, for most purposes the characterization of the concentration fluctuations requires knowledge of the concentration probability density function (PDF) in the point of interest and even the time evolution of the concentration. We firstly review the experimental works made both in the field and in the laboratory, and cover both point sources and line sources. Regarding modelling approaches, we cover analytical, semi-analytical, and numerical methods. For clarity of presentation we subdivide the models in two groups, models linked to a transport equation, which usually require a numerical resolution, and models mainly based on phenomenological aspects of dispersion, often providing analytical or semi-analytical relations. The former group includes: large-eddy simulations, Reynolds-averaged Navier–Stokes methods, two-particle Lagrangian stochastic models, PDF transport equation methods, and heuristic Lagrangian single-particle methods. The latter group includes: fluctuating plume models, semi-empirical models for the concentration moments, analytical models for the concentration PDF, and concentration time-series models. We close the review with a brief discussion highlighting possible useful additions to experiments and improvements to models.

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“…These limitations can be overcome by replacing the HWA with a Laser Doppler Anemometry (LDA) and coupling the latter with a FID. This approach was actually used to investigate the scalar dispersion within urban-like geometries (Contini et al, 2006;Carpentieri and Robins, 2010;Carpentieri et al, 2012;Kukačka et al, 2012;Nosek et al, 2016;Marucci and Carpentieri, 2020). Even the adoption of a LDA-FID system however has to face some metrological problems, namely to:…”

Section: Introductionmentioning

confidence: 99%

High-frequency simultaneous measurements of velocity and concentration within turbulent flows in wind-tunnel experiments

et al. 2020

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We analyse the metrological aspect related to systems devoted to the simultaneous measurements of (one point) velocity and scalar concentration statistics. We consider systems based on the coupling of an anemometer (Laser Doppler or Hot Wire) with a Flame Ionization Detector. In particular, we focus on the estimate of the cross-correlation velocity-concentration. Key aspects in the reliability of such measurements are related to the identification of an optimal distance between the two probes, the time lag with which the velocity and concentration signals are acquired, and, eventually, the influence of seeding particles (when using a Laser Doppler Anemometer) on the concentration measurements. We investigate these aspects by performing wind-tunnel experiments on the scalar dispersion down wind a ground-level source in a turbulent boundary layer. This analysis allowed us to identify a time delay and a convenient distance between the signals provided by the anemometer and the concentration detector. Results also show that the seeding used for the Laser Doppler Anemometer measurements modifies the cutoff frequency in the concentration spectra and induces a slightly larger uncertainty on the statistics of scalar field. The results show the reliability of both systems in estimating (horizontal and vertical) turbulent mass fluxes.

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Dispersion in an array of buildings in stable and convective atmospheric conditions

Cited by 28 publications

References 26 publications

Stable and convective boundary-layer flows in an urban array

Stable and convective boundary-layer flows in an urban array

Concentration Fluctuations from Localized Atmospheric Releases

High-frequency simultaneous measurements of velocity and concentration within turbulent flows in wind-tunnel experiments

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