Wind Resource Assessment in Building Environment: Benchmarking of Numerical Approaches and Validation with Wind Tunnel Data (original) (raw)
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Journal of Wind Engineering and Industrial Aerodynamics, 2018
This article presents a review on computational fluid dynamics (CFD) applied to urban wind energy exploitation. The content comprises technical CFD aspects relevant for this application and the current state-of-the-art in building aerodynamics applied to urban wind energy. The majority of studies (more than 50% of the respective criteria) used Reynolds-averaged Navier-Stokes (RANS) turbulence models, the commercial solver ANSYS, simulated a full-scale geometry and studied an isolated building. For RANS, at least second order-accurate discretization schemes must be used, to improve turbulence kinetic energy prediction. In large-eddy simulation (LES) studies, a blending scheme is often needed to avoid numerical instability. Urban wind flow is very complex (i.e. detachment, stagnation), and rigorous validation and verification processes are needed, because only sophisticated turbulence models are able to yield acceptable results. The building-roof shape was optimized for the wind energy exploitation attending to both turbulence intensity and wind velocity. Conventional roof and roof edge shapes were studied, as well as the compatibility with the installation of solar panels. Wind turbines sitting was also discussed. Few simulations of wind turbines installed on building roofs were conducted using wind turbine models, whereas real geometries of vertical axis wind turbines were simulated and optimized.
Towards wind modelling for sustainable building/urban design
IOP Conference Series: Earth and Environmental Science, 2020
In view of climate change and resource depletion the analysis of wind impact on built environment could be used for conscious building/urban design protecting humans against high winds but also taking advantage of wind forces in terms of ventilation of spaces or production of wind-driven energy. There is a strong need of developing the modelling technology that would enable predictive studies in this field. Climate change mitigation and adaptation became the point of departure to introduce the notions of risk/chance analysis that could help to examine the architectural/urban design from the holistic perspective. The need of addressing different parts of wind velocity spectrum is acknowledged. The steps forming the process of design for sustainable wind environment are listed. Both the necessary test activities, and the simulation ones, as well as, the ones leading to the application of risk/chance assessment are discussed. Wind thresholds referring to different aspects, levels and s...
Energies
This research presents a validation methodology for computational fluid dynamics (CFD) assessments of rooftop wind regime in urban environments. A case study is carried out at the Donadeo Innovation Centre for Engineering building at the University of Alberta campus. A numerical assessment of rooftop wind regime around buildings of the University of Alberta North campus has been performed by using 3D steady Reynolds-averaged Navier–Stokes equations, on a large-scale high-resolution grid using the ANSYS CFX code. Two methods of standard deviation (SDM) and average (AM) were introduced to compare the numerical results with the corresponding measurements. The standard deviation method showed slightly better agreements between the numerical results and measurements compared to the average method, by showing the average wind speed errors of 10.8% and 17.7%, and wind direction deviation of 8.4° and 12.3°, for incident winds from East and South, respectively. However, the average error bet...
Wind quantification in urban environments
2008
There is today a real lack of scientific studies and simple design tools to understand wind flows around buildings. This research is based on a great number of CFD (computational fluid dynamics) simulations carried out with FLUENT software to evaluate wind comfort at pedestrian level. This paper describes first the wind comfort criteria chosen. It then develops the process used for validating FLUENT software for wind studies in dense urban environments by comparing our simulations results with wind tunnel tests. This validation shows that wind mean velocities around buildings can be simulated numerically with a very high degree of accuracy. Based on the results of our simulations, we developed simple graphical tools to quantify critical wind speeds around buildings. This article should thus help in practice architects and town planners to design our built environment. Moreover, this paper shows how numerical modelling is now a high-performance tool to work out useful guidelines and simple design tools for urban planners.
Computational evaluation of wind loads on buildings: a review
This paper reviews the current state-of-the-art in the numerical evaluation of wind loads on buildings. Important aspects of numerical modeling including (i) turbulence modeling, (ii) inflow boundary conditions, (iii) ground surface roughness, (iv) near wall treatments, and (vi) quantification of wind loads using the techniques of computational fluid dynamics (CFD) are summarized. Relative advantages of Large Eddy Simulation (LES) over Reynolds Averaged Navier-Stokes (RANS) and hybrid RANS-LES over LES are discussed based on physical realism and ease of application for wind load evaluation. Overall LES based simulations seem suitable for wind load evaluation. A need for computational wind load validations in comparison with experimental or field data is emphasized. A comparative study among numerical and experimental wind load evaluation on buildings demonstrated generally good agreements on the mean values, but more work is imperative for accurate peak design wind load evaluations. Particularly more research is needed on transient inlet boundaries and near wall modeling related issues. and suburban terrain. Additionally, the National Building Code of Canada 2005 (NBCC 2005) provides acceleration calculations for the along-wind and across-wind directions. The Australian/New Zealand Standards (AS-NZ) (2002) code and the Architectural Institute of Japan (AIJ) recommendations (2400a) have made an exceptional attempt to provide the across-wind response using a cross-wind spectrum and expressions for both the across-wind and torsional root-mean-square acceleration. For cases not addressed by the building codes and standards, a physical testing in a boundary layer wind tunnel (BLWT) is referred. Although this option is economically viable for large projects such as the aerodynamics of tall buildings and long span bridges, performing building specific BLWT testing might not be cost-effective for most buildings such as low-rise residential buildings. Moreover, the variations in the wind flow and surrounding conditions that result from one project may not be extendable to a new project making generalizations more difficult. To address this gap at least for a preliminary wind load evaluation case, a computational model that can simulate the atmospheric boundary layer (ABL) flow and predict the parameters of interest can be an alternative approach. It is to be noted, however, computational approaches also have their own share of challenges and shortcomings yet to be resolved before their use for a final wind resistant design of buildings immersed in a turbulent ABL flows. At present, the cost of performing CFD is not lower than BLWT testing either. However, the computational cost is in a decreasing trend due to encouraging advances both in the hardware and software technology. This paper attempts to present a comprehensive review of the state-of-the-art of Computational Wind Engineering (CWE) as it relates to wind load evaluation on buildings. Recognizing significant progress made in the last decades, the paper will also pinpoint the area where the current practice of CFD needs further improvement, and attempts to discuss the direction of future CWE avenues based on the literature and authors' perspective, and draw some observatory conclusions relevant for practical applications of CWE.
Numerical Tools Dedicated to Wind Engineering in Large Urban Area
World Journal of Engineering and Technology, 2016
This paper presents a global methodology to compute wind flow in complex urban areas in order to assess wind pedestrian comfort, wind energy, wind safety or natural ventilation potential. The numerical tool presented here is composed of a CFD software suite covering both regional scale (20 km) and urban scale (1km), and able to model the wind in any complex terrains and in large urban environments. Examples are presented in the paper in order to show the advantages of the methodology for urban designers.
464: Wind quantification in urban environments
2008
There is today a real lack of scientific studies and simple design tools to understand wind flows around buildings. This research is based on a great number of CFD (computational fluid dynamics) simulations carried out with FLUENT software to evaluate wind comfort at pedestrian level. This paper describes first the wind comfort criteria chosen. It then develops the process used for validating FLUENT software for wind studies in dense urban environments by comparing our simulations results with wind tunnel tests. This validation shows that wind mean velocities around buildings can be simulated numerically with a very high degree of accuracy. Based on the results of our simulations, we developed simple graphical tools to quantify critical wind speeds around buildings. This article should thus help in practice architects and town planners to design our built environment. Moreover, this paper shows how numerical modelling is now a high-performance tool to work out useful guidelines and ...
Roof region dependent wind potential assessment with different RANS turbulence models
Journal of Wind Engineering and Industrial Aerodynamics, 2015
The analysis of the wind flow around buildings has a great interest from the point of view of the wind energy assessment, pollutant dispersion control, natural ventilation and pedestrians wind comfort and safety. Since LES turbulence models are computationally time consuming when applied to real geometries, RANS models are still widely used. However, RANS models are very sensitive to the chosen turbulence parametrisation and the results can vary according to the application. In this investigation, the simulation of the wind flow around an isolated building is performed using various types of RANS turbulence models in the open source code OpenFOAM, and the results are compared with benchmark experimental data. In order to confirm the numerical accuracy of the simulations, a grid dependency analysis is performed and the convergence index and rate are calculated. Hit rates are calculated for all the cases and the models that successfully pass a validation criterion are analysed at different regions of the building roof, and the most accurate RANS models for the modelling of the flow at each region are identified. The characteristics of the wind flow at each region are also analysed from the point of view of the wind energy generation, and the most adequate wind turbine model for the wind energy exploitation at each region of the building roof is chosen.