Publications

Fenomen gorodskogo ostrova tepla

On the effect of wind direction and urban surroundings on natural ventilation of a large semi-enclosed stadium

Influence of avenue-trees on air quality at the urban neighborhood scale. Part I: Quality assurance studies and turbulent Schmidt number analysis for RANS CFD simulations

A multi-fidelity wind surface pressure assessment via machine learning: A high-rise building case

CFD simulation of pollutant dispersion in a street canyon: Impact of idealized and realistic sources

Pollutant dispersion is of great relevance for people living in urban areas. High levels of pollutant can usually result from the combination of poor natural ventilation and high-traffic volumes of vehicles. Idealized point and line sources are commonly used to reproduce traffic emissions in simplified portions of urban areas, as street canyons. However, a limited number of studies focuses on the usage of realistic sources, as real car geometries which can influence the flow characteristics and the pollutant distribution inside the canyon. This is also the goal of the present paper for which Computational Fluid Dynamics (CFD) simulations were performed by means of scale-adaptive simulation (SAS) on a street canyon to investigate the impact of idealized and realistic sources. In stage 1 , SAS simulations were performed with idealized line sources by reproducing reduced-scale wind-tunnel (WT) experiments. In stage 2 , SAS simulations were carried out on a street canyon using idealized line sources and realistic sources with different levels of simplification. The results showed that the use of realistic sources can result in an increased concentration of 1.03 - 6.76 (at z = 0.33 m above the ground), with respect to the use of idealized line sources. Overall, at the lower level of the street canyon (e.g. z < 1.5 m), the concentration can be strongly affected by the presence of the car bodies. The results of the present study are expected to help urban planners as well as governmental institutions to reduce pollutant concentrations in the street canyon.

CFD ANALYSIS OF NATURAL VENTILATION IN LARGE SEMI-ENCLOSED BUILDINGS - CASE STUDY: AMSTERDAM ARENA FOOTBALL STADIUM

Large modern sports stadia are often multifunctional buildings that are not only used for sports purposes but also for other events such as concerts, conferences and festivities. Some of the stadia that have been built in recent years in north-western Europe are equipped with a semi-transparent roof that can be opened and closed, depending on the weather conditions and on the type of event. Whereas the roof is often open for sports events, it is often closed for concerts, conferences and festivities. This allows sheltering the indoor stadium environment from wind, rain and snow. A matter of concern related to such facilities is the natural ventilation, since HVAC systems are often not incorporated. This paper presents a numerical (CFD) and an experimental analysis of natural ventilation in a large semi-indoor multifunctional stadium in the Netherlands. CFD validation is performed based on full-scale wind speed measurements. Different alternative ventilation configurations are studied, including widening the existing openings and adding new openings at a few positions. It is shown that adding small openings near roof-height can increase the natural ventilation rate by up to 43%. A particular feature of this study is the coupled simulation of the wind flow in the urban environment around the stadium and the air flow inside the stadium on a high-resolution grid.

Measurements of wind effects on the efficacy of asbestos containment in a high-rise building

To prevent exposures during asbestos abatement process in buildings, it is often required to create a dynamic containment zone through the development of a depressurized area. The magnitude of the required depressurization is calculated for steady wind conditions and varies in the national regulations of each country. In current practice, the differential pressure between the containment zone’s outer surface and its interior is monitored to ensure that containment is ensured. However, wind is an unsteady phenomenon that has an impact on the external pressures acting on a building. This paper highlights the necessity for standard practice to take the effects of unsteady wind into account. For this paper, the effects of wind-induced pressure fluctuations on the performance of a containment zone were monitored in an asbestos abatement site in a high-rise building. Full-scale measurements were performed, simultaneously measuring pressure differences between the containment zone and its adjacent zones, and the wind velocity above the building’s rooftop. Although the measurements showed that for low wind velocities containment was ensured, it was momentarily breached for moderate wind velocities. It is also shown that the measurement location of pressure differences between the containment zone and its exterior is therefore important.

Wind-driven rain load on building enclosures - towards the reliable prediction of absorption and evaporation

CFD simulations of running aerodynamics: Impact of computational parameters

Validation of external BES-CFD coupling by inter-model comparison

Conflation of computational fluid dynamics (CFD) and building energy simulation (BES) has been used in recent years in order to improve the estimation of surface coefficients for studies on thermal comfort, mold growth and other performance aspects of a building. BES can provide more realistic boundary conditions for CFD, while CFD can provide higher resolution modelling of flow patterns within air volumes and convective heat transfer coefficients (CHTC) for BES. BES and CFD can be internally or externally coupled. Internal coupling is the traditional way of expanding software by which the code is expanded by adding new modules and it entails a lot of effort in terms of debugging, maintenance etc. On the other hand, by external coupling different existing numerical packages work together, using the latest advances already implemented in them. This paper focuses on the validation of a newly developed prototype performing the external coupling of BES and CFD. The validation procedure involves an inter-model comparison between a conjugate heat transfer model and the prototype.

Towards grid resolution guidelines for CFD simulations of wind speed in passages between buildings

CFD simulations of the wind speed conditions in passages between generic parallel building configurations have been performed to initiate the development of grid resolution guidelines. CFD validation is conducted based on published wind tunnel data. At least for the cases studied here, the minimum required grid resolution across the passage width is a function of the passage width and the building influence scale. A preliminary grid resolution guideline is provided and some information for the development of additional guidelines is given.

Computational modeling of evaporative cooling to reduce air temperatures during heat waves with application to Bergpolder Zuid

Numerical analysis of flow in a 90 degrees bend for a low-speed wind tunnel

The influence of a 90° bend on the characteristics of the flow in a low-speed wind tunnel is investigated with CFD (Computational Fluid Dynamics). CFD validation is performed based on published experimental data. The investigated bend is designed to preserve a uniform velocity inlet profile and a low turbulence level. The influence of bend curvature is assessed. Moreover, the effect of the presence, the number and the spacing of guide vanes is investigated. Two turbulence models are evaluated in the numerical simulations. Bends with a weak curvature and guide vanes are found to perform best in preserving a uniform velocity inlet profile. Comparing guide vanes with equal and variable spacing, the latter results in better flow uniformity in the centre of the duct, downstream of the bend, but not at the outside. A considerable increase in turbulence level is noticed for all configurations investigated. The turbulence has a significant anisotropic character indicating the need for turbulence models that can account for anisotropy in this type of studies.

WITHDRAWN: CFD evaluation of wind speed conditions in passages between parallel buildings – effect of wall-function roughness modifications for the atmospheric boundary layer flow

Validation of CFD simulations of wind-driven rain on a low-rise building facade

CFD simulation of pedestrian-level wind conditions around buildings: Past achievements and prospects

Counter-gradient diffusion in a slot-ventilated enclosure assessed by LES and RANS

Çeviri: Gerçek Anlamda Korkunç Bir Makale Yazmak İçin 10 İpucu (10 Tips for Writing a Truly Terrible Journal Article)

“Gunumuzde yayin baskisi ve yayinlarin miktari artarken yayinlarin ortalama kalitesinin azaldigi gorulmektedir, bu yuzden daha kariyerinin basinda olan arastirmacilara, dergi makalelerinin nasil yazilmasi gerektigi konusunda rehberlik etmek giderek onem kazanmaktadir. Daha once [bununla ilgili] iyi hazirlamis bircok [yazim] kilavuz ve [yazim] kurallar yayinlanmis olsa da bu makalede kesinlikle yapmamaniz gereken 10 seyin altini cizerek farkli bir yaklasim benimsenmektedir. Ben bu on seyi temel bilimlerdeki tecrubelerime dayandirdim fakat bunlarin bazilari disiplininiz ne olursa olsun dogrulugundan bir sey kaybetmeyecek olan seylerdir.”