Publications

High-resolution wind-driven rain measurements on a low-rise building—experimental data for model development and model validation

Verkennende analyse van het windenergiepotentieel in de gebouwde omgeving in Nederland

CFD simulation of aerodynamic forces on the DrivAer car model: Impact of computational parameters

Automobile designers and engineers are constantly focusing on aerodynamic optimization with the aim of reducing fuel consumption and particulate and gaseous emissions. In the last decade, a generic car body called DrivAer model has been frequently adopted in numerical and experimental investigations. However, the setup of the CFD domain, grid, turbulence model and numerical approach can significantly impact the accuracy of results and requires sensitivity studies. This is the goal of this study for which wind-tunnel (WT) tests and CFD simulations were carried out on the 1:4 reduced-scale DrivAer notchback model. The target parameters were the drag (CD) and lift (CL) coefficients. First, the CFD results were validated with the WT tests. Next, the impact of surface grid resolution, total prism layer height, first prism layer height, growth rate, cell type, upstream and downstream distances, turbulence models, and numerical approaches was systematically investigated. The sensitivity analysis provides a set of guidelines on optimal grid generation. The validation study indicates that a hybrid RANS-LES approach is a good trade-off for an accurate yet economical simulation of the aerodynamic forces. These guidelines are expected to help researchers and practitioners in CFD simulations of car aerodynamics.

Aerodynamic drag in competitive tandem para-cycling: Road race versus time-trial positions

An athlete's riding posture is a key element for aerodynamic drag in cycling. Tandem cycling has the complication of having two athletes in close proximity to each other on a single tandem bicycle. The complex flow-field between the pilot and stoker in tandem cycling presents new challenges for aerodynamic optimisation. Aerodynamic drag acting on two tandem road race setups and two track time-trial setups were analysed with computational fluid dynamics (CFD) simulations. For validation purposes, wind tunnel measurements were designed providing drag measurements from both tandem athletes simultaneously using a quarter-scale model. A max drag force deviation of 4.9% was found between the wind tunnel experiments and CFD simulations of the quarter-scale geometry. Full-scale CFD simulations of upright, crouched, time-trial and frame-clench tandem setups were performed. The drag force experienced by individual athletes in all investigated tandem setups was compared to that of solo riders to enhance understanding of the aerodynamic interaction between both tandem athletes. The most aerodynamic tandem setup was found to be the frame-clench setup which is unique to tandem cycling and had a CDA of 0.286 m2, and could provide an advantage of 8.1 s over a standard time-trial setup for a 10 km time-trial event.

The influence of wind direction on natural ventilation: application to a large semi-enclosed stadium

Natural ventilation is still a commonly applied way in building engineering to ensure a healthy and comfortable indoor climate. In this paper CFD simulations of the natural ventilation of a large semi-enclosed stadium in the Netherlands during the summer are described. Simulations are performed to assess the air exchange rate for a total of eight wind directions. The CFD model consists of both the complex stadium geometry and the urban environment in which the stadium is located. Validation of the CFD model is performed using full-scale 3D wind velocity measurements, furthermore, a grid sensitivity analysis is conducted. Comparison of the calculated air exchange rates showed that the wind direction has a significant effect on the air exchange rate; differences up to 100% were found for the air exchange rate, which can be explained by looking at the presence and size of the buildings that are situated upstream of the stadium.

On the use of CFD for modelling air pollutant dispersion around buildings

On the validity of numerical wind-driven rain simulation on a rectangular low-rise building under various oblique winds

Impact of inflow methods and aerodynamic roughness lengths on the streamwise homogeneity of flow profiles in LES of the neutral ABL

In Computational Fluid Dynamics (CFD) simulations of the atmospheric boundary layer (ABL) the relation between inflow conditions and wall boundary conditions has been thoroughly investigated for Reynolds-averaged Navier-Stokes (RANS) modeling, whereas it yet needs to be evaluated for Large Eddy Simulations (LES). In the present paper streamwise homogeneity of flow profiles for LES of the neutral ABL over surfaces with different aerodynamic roughness lengths in combination with three different inflow turbulence generation methods is investigated. Specifically, one precursor and two synthetic methods have been considered along with three aerodynamic roughness lengths. The results show that the precursor method satisfactorily preserves the homogeneity of both mean velocity and turbulence kinetic energy, with respective average deviations up to 0.7% and 3.5% from target profiles at the outlet of the domain. Among the synthetic methods, less accurate but also less computationally demanding than the precursor method, the Vortex Method greatly outperforms the Spectral Synthesizer in terms of both mean velocity and turbulence kinetic energy. Lastly, terrain roughness is found to have only a weak influence on the performance of the inflow methods considered.

Development, Application and Verification of a Numerical Model for Spatial and Temporal Rain Load Distribution

COVID-19 と風工学：アイントホーフェン工科大学とルーヴェン・カトリック大学の貢献

Computational Wind Engineering: Theory and Applications

On the impact of climate change on urban microclimate, thermal comfort, and human health: Multiscale numerical simulations

Climate change is expected to exacerbate urban microclimatic conditions and have adverse effects on human morbidity and mortality. However, there is limited knowledge on the impact of climate change on urban microclimate and human health for actual urban areas. In this study, we investigate the impact of climate change on urban microclimate and pedestrian thermal comfort within a complex district in Nicosia, Cyprus. Two climatic scenarios are considered: (i) current scenario based on meteorological conditions derived from field measurements performed in 2010, and (ii) future scenario for which meteorological conditions of 2050 are based on downscaled Regional Climate Models (RCMs). URANS CFD simulations are performed for the period of 9 to 10 July with a one-hour time-step. The results show that by 2050, the maximum air temperature at the pedestrian height of the case study area can increase by 2.3 °C which can increase heat-related mortality by more than 240%. In addition, the UTCI is expected to significantly increase especially in the afternoon hours with up to a 4.3 °C increase at 20:00. The "very strong heat stress" conditions (UTCI: 38-46 °C) are expected to prevail for a longer period during the day, increasing from 3.3 to 6.6 hours.

CFD simulation and validation of wind-driven rain on a building facade with an Eulerian multiphase model