575 publications from this institution
CFD simulations can be a powerful tool to investigate the relationship between stadium geometry and the wind flow pattern inside the stadium. The CFD model has to be validated to ensure reliable results. This paper presents a validation study by comparing the results of full-scale measurements and steady-state and transient CFD simulations of the wind flow pattern inside the Koning Boudewijn athletics stadium in Brussels. The comparison shows that transient CFD simulations are better able to predict the turbulent wind flow pattern inside the stadium compared to steady-state CFD simulations. Nevertheless, discrepancies remain, which are attributed to simplifications in model geometry and to the differences in inlet atmospheric turbulence between the measurements and the simulations.
In the past but especially more recently, some cyclists in triathlon and road cycling competitions have been riding with an object stuck between their chest and their shirt, attempting to reduce aerodynamic drag. This object has been referred to as "chest fairing". The most excessive examples occurred in triathlon, where large objects such as drink bottles were used as chest fairing. More exceptionally, smaller examples have been observed in road cycling in individual time trials (ITT), including the 2023 Tour de France ITT and the 2023 Glasgow Road World Championships ITT. To the best of our knowledge, this paper provides the first published scientific assessment of the benefits that can be obtained by different types of chest fairings. The assessment is performed by computational fluid dynamics (CFD) simulations validated with wind tunnel tests. A reference configuration of cyclist without chest fairing and seven chest fairing configurations are analysed. The resulting drag reduction can go up to 3.6%, but some chest fairings actually increase the drag. It is concluded that a chest fairing can be beneficial and potentially decisive but that careful and dedicated a priori wind tunnel tests or CFD simulations for the specific rider must be undertaken.
On-site renewable energy generation in the built environment can be achieved by incorporating wind turbines in the integral design of buildings. Passages through buildings are considered promising to strengthen the local wind resource availability but information concerning their design and performance is scarce. Therefore, two key design parameters that can enhance the wind energy performance of ducted openings in high-rise buildings are addressed and optimized via CFD simulations: the fillet radius (r) of the opening and the duct diameter (d0). 3D steady RANS simulations are performed and validated with wind tunnel data from the literature. Fillets are shown to suppress flow separation, thereby enhancing the magnitude and uniformity of the wind speed in the duct and reducing the turbulent kinetic energy. With a reference diameter d0 = D, the best-performing configuration has a normalized fillet radius r/d0 = 0.2, which increases the average wind speed in the duct by 65% and the wind power by 354%. Modifying the duct diameter alone has limited influence. However, combining a larger duct diameter d0 = 1.5D with fillets with r/d0 = 0.4, can yield up to 78% increase in average wind speed and 650% in wind power density. Findings indicate that the dimensionless wind speed in the duct (U/U0) scales closely in proportion to the normalized fillet radius (r/d0). With these results, the present study demonstrates the aerodynamic advantage of ducted openings in buildings and identifies relevant design conditions required to improve the wind resource availability for the prospective implementation of wind turbines.
The design and realization of a healthy indoor environment is a challenge that is investigated from different perspectives at the unit Building Physics and Systems (BPS; Faculty of Architecture, Building and Planning) of Eindhoven University of Technology. Performance requirements (for instance, with respect to air quality, thermal comfort and lighting) and performance based assessment methods are the point-of-departure, focusing at computational techniques supporting the design process. Different specific application fields such as dwellings, offices, schools, but also, operating theatres, churches, musea and multifunctional stadiums, underline the applied approach that is part of the research within the unit. In the design of healthy environments, the performance based design assessment is crucial in arriving at innovative design solutions and optimized indoor and outdoor environments. In this assessment computational support tools and experimental verification play an important role. However, assessing the right indicators in an objective way, applying the correct tools and correct application of these tools is not yet well established. Alongside, developments are still ongoing. The work performed in the unit by the different researchers relates to the research questions that can be derived from this notice. The paper gives an introduction to the Unit BPS and presents a brief overview of recent and ongoing research. An extensive list of references is provided for further reading and supports the conclusion that healthy environments can and should be addressed from a wide angle.
The global trend towards urbanization has increased the popularity and the number of studies in the field of urban physics. Computational Fluid Dynamics (CFD) is one of the tools that can help researchers to investigate the effect of urban microclimate on comfort, health and energy demand. In this study, CFD simulations of the wind flow in a generic urban configuration are performed with a commercial (ANSYS Fluent) and an open source (OpenFOAM) CFD solver. The 3D Reynolds-averaged Navier-Stokes (RANS) equations are solved in combination with the standard k-e and the realizable k-e turbulence models. Results showed that both of the solvers were fairly good in predicting the wind velocities at the area of interest. Compared to the wind tunnel measurements, the simulations predicted wind velocity ratios with a correlation coefficient of 0.76, 0.77, 0.75 and 0.74 for ANSYS Fluent standard k-e, ANSYS Fluent realizable k-e, OpenFOAM standard k-e and OpenFOAM realizable k-e respectively.
There is probably no rule as applicable to the activity of peer review as the so-called “golden rule” or law of reciprocity: do not treat others in ways that you do not want to be treated yourself. This holds for the relation of the peer reviewer to the authors, the editor, and even the wider scientific community. As publication pressure and the quantity of submissions continue to increase, so does the need for high-quality peer reviews. Several best practice guidelines and rules have been published before. This document takes a different approach, by highlighting 10 things you should certainly NOT do. I’ve based them on my experiences in the exact sciences/engineering fields, but some of them may well hold true, whatever your discipline.
The last decades, newly built large sports stadia are also increasingly being used for other events such as concerts, conferences and other activities. An example of such a modern multifunctional stadium is the Amsterdam ‘ArenA’ in the Netherlands. This stadium is equipped with a roof that can be opened and closed depending on the weather conditions and the type of event. No HVAC systems are present to control the conditions of the relatively large indoor air volume (~106 m3). When the roof is closed, the large number of spectators and insufficient natural ventilation can lead to problems concerning the indoor air quality, while overheating can be an additional problem in summer. Full-scale measurements were performed to assess the current indoor climate and air exchange rate. In addition, CFD simulations were performed to analyse the air exchange rate in the current configuration and the air exchange rates of four alternative ventilation configurations. CFD was preferred for this study for the detailed simulation of air flow through the relatively small ventilation openings, the discharge coefficients of which are unknown. The CFD simulations showed that the air exchange rate can be increased with up to 43% by creating additional openings in the upper part of the stadium.
Despite the establishment of CFD as a tool for calculating the amount of wind-driven rain (WDR) falling onto building facades, very few efforts have been made towards the validation of CFD for this purpose. This paper presents part of a detailed CFD validation study that was conducted at the Laboratory of Building Physics, supported by a new experimental wind, rain and WDR database for a low-rise building. It will be shown that numerical simulation, if conducted with care, can provide quite accurate predictions of the amount of WDR impinging on the building facade and that the main discrepancies in this case were due to a simplification of the upstream wind conditions in the numerical model.
Traffic pollutant concentrations at the pedestrian level in a generic urban neighborhood were studied. Scenarios without and with avenue-trees were investigated with Computational Fluid Dynamics (CFD) by employing a Reynolds Stress Model (RSM) to which extra terms are added accounting for the effects of vegetation on the wind. The avenue-trees showed a significant impact on the traffic pollutant dispersion and flow fields in the street canyons and intersections. In the presence of trees, a faster build-up of concentrations was found for the wind-parallel streets. In the wind-perpendicular streets, considerably higher pollutant concentrations at the buildings’ leeward walls were found.
