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“CFD modelling of small particle dispersion: the influence of the turbulence kinetic energy in the atmospheric boundary layer”. Gorlé, C, van Beeck J, Rambaud P, Van Tendeloo G, Atmospheric environment : an international journal 43, 673 (2009). http://doi.org/10.1016/j.atmosenv.2008.09.060
Abstract: When considering the modelling of small particle dispersion in the lower part of the Atmospheric Boundary Layer (ABL) using Reynolds Averaged Navier Stokes simulations, the particle paths depend on the velocity profile and on the turbulence kinetic energy, from which the fluctuating velocity components are derived to predict turbulent dispersion. It is therefore important to correctly reproduce the ABL, both for the velocity profile and the turbulence kinetic energy profile. For RANS simulations with the standard kå model, Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the kå turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 4647, 145153.) proposed a set of boundary conditions which result in horizontally homogeneous profiles. The drawback of this method is that it assumes a constant profile of turbulence kinetic energy, which is not always consistent with field or wind tunnel measurements. Therefore, a method was developed which allows the modelling of a horizontally homogeneous turbulence kinetic energy profile that is varying with height. By comparing simulations performed with the proposed method to simulations performed with the boundary conditions described by Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the kå turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 4647, 145153.), the influence of the turbulence kinetic energy on the dispersion of small particles over flat terrain is quantified.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.629
Times cited: 79
DOI: 10.1016/j.atmosenv.2008.09.060
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“A comprehensive modelling approach for the neutral atmospheric boundary layer : consistent inflow conditions, wall function and turbulence model”. Parente A, Gorlé, C, van Beeck J, Benocci C, Boundary-layer meteorology 140, 411 (2011). http://doi.org/10.1007/s10546-011-9621-5
Abstract: We report on a novel approach for the Reynolds-averaged Navier-Stokes (RANS) modelling of the neutral atmospheric boundary layer (ABL), using the standard k− turbulence model. A new inlet condition for turbulent kinetic energy is analytically derived from the solution of the k− model transport equations, resulting in a consistent set of fully developed inlet conditions for the neutral ABL. A modification of the standard k− model is also employed to ensure consistency between the inlet conditions and the turbulence model. In particular, the turbulence model constant C μ is generalized as a location-dependent parameter, and a source term is introduced in the transport equation for the turbulent dissipation rate. The application of the proposed methodology to cases involving obstacles in the flow is made possible through the implementation of an algorithm, which automatically switches the turbulence model formulation when going from the region where the ABL is undisturbed to the region directly affected by the building. Finally, the model is completed with a slightly modified version of the Richards and Hoxey rough-wall boundary condition. The methodology is implemented and tested in the commercial code Ansys Fluent 12.1. Results are presented for a neutral boundary layer over flat terrain and for the flow around a single building immersed in an ABL.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.573
Times cited: 54
DOI: 10.1007/s10546-011-9621-5
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“Dispersion in the wake of a rectangular building : validation of two Reynolds-averaged Navier-Stokes modelling approaches”. Gorlé, C, van Beeck J, Rambaud P, Boundary-layer meteorology 137, 115 (2010). http://doi.org/10.1007/s10546-010-9521-0
Abstract: When modelling the turbulent dispersion of a passive tracer using Reynolds-averaged Navier-Stokes (RANS) simulations, two different approaches can be used. The first consists of solving a transport equation for a scalar, where the governing parameters are the mean velocity field and the turbulent diffusion coefficient, given by the ratio of the turbulent viscosity and the turbulent Schmidt number Sc (t) . The second approach uses a Lagrangian particle tracking algorithm, where the governing parameters are the mean velocity and the fluctuating velocity field, which is determined from the turbulence kinetic energy and the Lagrangian time T (L) . A comparison between the two approaches and wind-tunnel data for the dispersion in the wake of a rectangular building immersed in a neutral atmospheric boundary layer (ABL) is presented. Particular attention was paid to the influence of turbulence model parameters on the flow and concentration field. In addition, an approach to estimate Sc (t) and T (L) based on the calculated flow field is proposed. The results show that applying modified turbulence model constants to enable correct modelling of the ABL improves the prediction for the velocity and concentration fields when the modification is restricted to the region for which it was derived. The difference between simulated and measured concentrations is smaller than 25% or the uncertainty of the data on 76% of the points when solving the transport equation for a scalar with the proposed formulation for Sc (t) , and on 69% of the points when using the Lagrangian particle tracking with the proposed formulation for T (L) .
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.573
Times cited: 16
DOI: 10.1007/s10546-010-9521-0
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“Stack gas dispersion measurements with large scale-PIV, aspiration probes and light scattering techniques and comparison with CFD”. Nakiboglu G, Gorlé, C, Horvath I, van Beeck J, Blocken B, Atmospheric environment : an international journal 43, 3396 (2009). http://doi.org/10.1016/j.atmosenv.2009.03.047
Abstract: The main purpose of this research is to manage simultaneous measurement of velocity and concentration in large cross-sections by recording and processing images of cloud structures to provide more detailed information for e.g. validation of CFD simulations. Dispersion from an isolated stack in an Atmospheric Boundary Layer (ABL) was chosen as the test case and investigated both experimentally and numerically in a wind tunnel. Large Scale-Particle Image Velocimetry (LS-PIV), which records cloud structures instead of individual particles, was used to obtain the velocity field in a vertical plane. The concentration field was determined by two methods: Aspiration Probe (AP) measurements and Light Scattering Technique (LST). In the latter approach, the same set of images used in the LS-PIV was employed. The test case was also simulated using the CFD solver FLUENT 6.3. Comparison between AP measurements and CFD revealed that there is good agreement when using a turbulent Schmidt number of 0.4. For the LST measurements, a non-linear relation between concentration and light intensity was observed and a hyperbolic-based function is proposed as correction function. After applying this correction function, a close agreement between CFD and LST measurements is obtained. (C) 2009 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.629
Times cited: 15
DOI: 10.1016/j.atmosenv.2009.03.047
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“Application of improved CFD modeling for prediction and mitigation of traffic-related air pollution hotspots in a realistic urban street”. Lauriks T, Longo R, Baetens D, Derudi M, Parente A, Bellemans A, van Beeck J, Denys S, Atmospheric Environment 246, 118127 (2021). http://doi.org/10.1016/J.ATMOSENV.2020.118127
Abstract: The correct prediction of air pollutants dispersed in urban areas is of paramount importance to safety, public health and a sustainable environment. Vehicular traffic is one of the main sources of nitrogen oxides (NO ) and particulate matter (PM), strongly related to human morbidity and mortality. In this study, the pollutant level and distribution in a section of one of the main road arteries of Antwerp (Belgium, Europe) are analyzed. The assessment is performed through computational fluid dynamics (CFD), acknowledged as a powerful tool to predict and study dispersion phenomena in complex atmospheric environments. The two main traffic lanes are modeled as emitting sources and the surrounding area is explicitly depicted. A Reynolds-averaged Navier–Stokes (RANS) approach specific for Atmospheric Boundary Layer (ABL) simulations is employed. After a validation on a wind tunnel urban canyon test case, the dispersion within the canopy of two relevant urban pollutants, nitrogen dioxide (NO) and particulate matter with an aerodynamic diameter smaller than 10 m (PM10), is studied. An experimental field campaign led to the availability of wind velocity and direction data, as well as PM10 concentrations in some key locations within the urban canyon. To accurately predict the concentration field, a relevant dispersion parameter, the turbulent Schmidt number, , is prescribed as a locally variable quantity. The pollutant distributions in the area of interest – exhibiting strong heterogeneity – are finally demonstrated, considering one of the most frequent and concerning wind directions. Possible local remedial measures are conceptualized, investigated and implemented and their outcomes are directly compared. A major goal is, by realistically reproducing the district of interest, to identify the locations inside this intricate urban canyon where the pollutants are stagnating and to analyze which solution acts as best mitigation measure. It is demonstrated that removal by electrostatic precipitation (ESP), an active measure, and by enhancing the dilution process through wind catchers, a passive measure, are effective for local pollutant removal in a realistic urban canyon. It is also demonstrated that the applied ABL methodology resolves some well known problems in ABL dispersion modeling.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3.629
DOI: 10.1016/J.ATMOSENV.2020.118127
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“Mapping of toxic vapours on board of tankers”. Jacobs W, Floren E, Luyckx D, Bueken P, van Beeck J, Van Grieken R, (2011)
Keywords: P3 Proceeding; Economics; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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