Modelling NOX concentrations through CFD-RANS in an urban hot-spot using high resolution traffic emissions and meteorology from a mesoscale model

Sánchez, Beatríz; Santiago, José Luis; Martilli, Alberto; Martín, Fernando López; Borge, Rafael; Quaassdorff, Christina Violetta; Paz, David de la

doi:10.1016/j.atmosenv.2017.05.022

Cited by 64 publications

(46 citation statements)

References 37 publications

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“…Unsteady CFD simulations of two weeks was not affordable due to large computational cost. For this reason, the methodology WA CFD-RANS (weighted average CFD-RANS simulations) [20,30,42] was employed. It used CFD simulations for several meteorological conditions and assumed the concentration was inversely proportional to wind speed.…”

Section: Evaluation Of the Modeling Approach Used In The Present Studymentioning

confidence: 99%

On the Impact of Trees on Ventilation in a Real Street in Pamplona, Spain

et al. 2019

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This paper is devoted to the quantification of changes in ventilation of a real neighborhood located in Pamplona, Spain, due to the presence of street trees Pollutant dispersion in this urban zone was previously studied by means of computational fluid dynamic (CFD) simulations. In the present work, that research is extended to analyze the ventilation in the whole neighborhood and in a tree-free street. Several scenarios are investigated including new trees in the tree-free street, and different leaf area density (LAD) in the whole neighborhood. Changes between the scenarios are evaluated through changes in average concentration, wind speed, flow rates and total pollutant fluxes. Additionally, wind flow patterns and the vertical profiles of flow properties (e.g., wind velocity, turbulent kinetic energy) and concentration, horizontally-averaged over one particular street, are analyzed. The approach-flow direction is almost perpendicular to the street under study (prevailing wind direction is only deviated 4º from the perpendicular direction). For these conditions, as LAD increases, average concentration in the whole neighborhood increases due to the decrease of wind speed. On the other hand, the inclusion of trees in the street produces an increase of averaged pollutant concentration only within this street, in particular for the scenario with the highest LAD value. In fact, the new trees in the street analyzed with the highest LAD value notably change the ventilation producing an increase of total pollutant fluxes inward the street. Additionally, pollutant dispersion within the street is also influenced by the reduction of the wind velocity along the street axis and the decrease of turbulent kinetic energy within the vegetation canopy caused by the new trees. Therefore, the inclusion of new trees in a tree-free street should be done by considering ventilation changes and traffic emissions should be consequently controlled in order to keep pollutant concentration within healthy levels.

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Section: Evaluation Of the Modeling Approach Used In The Present Studymentioning

confidence: 99%

On the Impact of Trees on Ventilation in a Real Street in Pamplona, Spain

et al. 2019

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“…A transport equation is used to simulate the dispersion of nitrogen oxides (NO x ), where diffusivity is related to turbulent viscosity divided by Schmidt number (Sc). Dispersion of NO x (regarded as NO + NO 2 ) is modelled in order to avoid the inclusion of chemical reactions in the CFD simulations since NO x can be considered as a non-reactive gas [24,35,36]. The aerodynamic effects of vegetation are modelled by means of a sink in the momentum equation (Su i , Equation (1)) and sinks/sources in turbulence equations (S k and S ε , Equations (2) and (3)).…”

Section: The Study Area and Modeling Set-upmentioning

confidence: 99%

The Impact of Planting Trees on NOx Concentrations: The Case of the Plaza de la Cruz Neighborhood in Pamplona (Spain)

et al. 2017

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Abstract:In this paper, the role of trees on airborne pollutant dispersion in a real neighborhood in Pamplona (Spain) is discussed. A Computational Fluid Dynamics (CFD) model is employed and evaluated against concentrations measured during the last part of winter season at a monitoring station located in the study area. Aerodynamic and deposition effects of trees are jointly considered, which has only been done in few recent studies. Specifically, the impact on NO x concentration of: (a) tree-foliage; and (b) introducing new vegetation in a tree-free street is analyzed considering several deposition velocities and Leaf Area Densities (LAD) to model deciduous and evergreen vegetation. Results show that the higher the LAD, the higher the deposition (concentration reduction) and the blocking aerodynamic effect (concentration increase). Regardless of foliage or deposition rates, results suggest the predominance of aerodynamic effects which induce concentration increases up to a maximum of 7.2%, while deposition induces concentration decreases up to a maximum of 6.9%. The inclusion of new trees in one street modifies the distribution of pollutant, not only in that street, but also in nearby locations with concentration increase or decrease. This finding suggests that planting trees in street with traffic as an air pollution reduction strategy seems to be not appropriate in general, highlighting the necessity of ad hoc studies for each particular case to select the suitable location of new vegetation.

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“…Although this could induce biases in the results since these are important parameters for pollutant concentrations description, some tests have been performed to analyse the accuracy of the modelling system. In this sense, modelled NO X concentrations have been compared to passive sampler's measurements across the domain showing good agreement (R = 0.72) ( Figure 5.24) (Sanchez et al, 2017b). (Sanchez et al, 2017b).…”

Section: No X Concentrations At Microscalementioning

confidence: 91%

“…In order to demonstrate the capabilities of the modelling system presented for this kind of assessment, a CFD simulation was performed for the FL area (and for Posco domain for validation purposes in section 6.2.3). The first coupling test consisted on a series of steadystate simulations with no reactive pollutants for this particular urban hot-spot (Sanchez et al, 2017b). The coupling to the CFD model STARCCM+ from CD-Adapco was tested in collaboration with the Atmospheric Pollution Modelling Group (GMCA initials in Spanish) from CIEMAT.…”

Section: Public Transport Bus Stops Relocationmentioning

confidence: 99%

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Development of a microscale traffic emission simulation system : application to Madrid for the definition of air quality improvement measures = Desarrollo de un sistema de simulación de emisiones del tráfico rodado a microescala : aplicación a Madrid para la definición de medidas de mejora de la calidad del aire

Quaassdorff¹

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Rafael Borge, for trusting me to carry out this work and for his guidance throughout the thesis. Especially for the opportunities that have arisen from this work and that have been possible due to his involvement. Of course, to all the coworkers from the TARIndustrial group and people from the Department of Industrial Chemistry and Environmental Engineering that travelled with me through this journey. With their help and good advice this work was improved. To the whole group of the TECNAIRE-CM project. Their effort and work has leed to very good results and many possibilities have arisen in this research line. To Ángeles Cristóbal from the Madrid City Council, Ana Rosa Llorente and Gregorio Vallejo from the Planning Department in the General Subdirectorate for the Implementation of Mobility and Transport for providing all the necessary permits and traffic data to carry out this work. Especial thanks to Dr. Robin Smit and Dr. Mark Hickman for their kindness by giving me the opportunity to carry out my international research stay at the University of Queensland. Also, for facilitating my professional and personal integration during my stay as well as providing all accesses to the necessary software (PΔP). I cannot forget the colleagues of the Fire and Transport Group of the School of Civil Engineering (AEB) who treated me as one more since the very first day. I would also like to thank Hans-Jurgen Don, Ignacio Galindo and Vidal Roca for supplying PTV software which has been fundamental for the accomplishment of this work. Also to Arjan Eijk from TNO for the help provided with the software VERSIT+ micro /ENVIVER. On the other hand also to Stefan Hausberger and Martin Dippold from TUGraz for providing PHEM and PHEM-light software's. And to Kyung-Hwan Kwak (Kangwon National University) for collaborating in the validation of the simulation system. Last but not least, to my family and all those people who during this time have always shown me their unconditional support, even in the hardest moments. Sincerely, thank you very much to all, I am sure that otherwise it would not have been possible. The value of a person is defined by V = (K + S) x A. Knowledge and Skills add up but, Attitude multiplies.

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Modelling NOX concentrations through CFD-RANS in an urban hot-spot using high resolution traffic emissions and meteorology from a mesoscale model

Cited by 64 publications

References 37 publications

On the Impact of Trees on Ventilation in a Real Street in Pamplona, Spain

On the Impact of Trees on Ventilation in a Real Street in Pamplona, Spain

The Impact of Planting Trees on NOx Concentrations: The Case of the Plaza de la Cruz Neighborhood in Pamplona (Spain)

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