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CFD validation studies of wind-driven rain on building facades. (a) VLIET test building in Leuven, Belgium (Blocken and Carmeliet 2005). (b) Catch ratio contours on the south-west facade after a rain event with south-west wind direction (Blocken and Carmeliet 2007b); (c) Cathedral of Learning; (d) Cathedral of Learning with surface soiling patterns (courtesy of Christopher Bailey 2010); (e) Catch ratios on the south-west facade for different reference wind speeds (Tang and Davidson 2004 – © Elsevier, reproduced with permission); (f) Hunting Lodge St. Hubertus in the Netherlands, with indication of moisture related damage (Briggen et al. 2009); (g) Comparison of measured (left) and simulated (right) catch ratios at the end of a rain event with wind direction perpendicular to the facade (Briggen et al. 2009).
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This article provides an overview of the application of computational fluid dynamics (CFD) in building performance simulation for the outdoor environment, focused on four topics: (1) pedestrian wind environment around buildings, (2) wind-driven rain on building facades, (3) convective heat transfer coefficients at exterior building surfaces and (4)...
Citations
... Computational Fluid Dynamics (CFD) (Anderson and Wendt, 1995) has transformed the way engineers study fluid behavior across disciplines from aerospace engineering (Slotnick et al., 2014), civil engineering (Blocken et al., 2011), to biomedical engineering (Doost et al., 2016). However, CFD simulation remains highly specialized and requires a wide range of expertise in fluid mechanics, numerical methods, geometric reasoning, and high-performance computing. ...
Computational Fluid Dynamics (CFD) is an essential simulation tool in various engineering disciplines, but it often requires substantial domain expertise and manual configuration, creating barriers to entry. We present Foam-Agent, a multi-agent framework that automates complex OpenFOAM-based CFD simulation workflows from natural language inputs. Our innovation includes (1) a hierarchical multi-index retrieval system with specialized indices for different simulation aspects, (2) a dependency-aware file generation system that provides consistency management across configuration files, and (3) an iterative error correction mechanism that diagnoses and resolves simulation failures without human intervention. Through comprehensive evaluation on the dataset of 110 simulation tasks, Foam-Agent achieves an 83.6% success rate with Claude 3.5 Sonnet, significantly outperforming existing frameworks (55.5% for MetaOpenFOAM and 37.3% for OpenFOAM-GPT). Ablation studies demonstrate the critical contribution of each system component, with the specialized error correction mechanism providing a 36.4% performance improvement. Foam-Agent substantially lowers the CFD expertise threshold while maintaining modeling accuracy, demonstrating the potential of specialized multi-agent systems to democratize access to complex scientific simulation tools. The code is public at https://github.com/csml-rpi/Foam-Agent
... While direct measurements are the most reliable way to characterize IAQ accurately, they are the most expensive, time-consuming, potentially hazardous, and difficult to apply for extensive parametric analyses. Therefore, researchers have advocated using numerical simulations in air quality assessment [47][48][49][50][51]. For instance, Ma and Zhou [52] investigated a sour gas well blowout scenario through CFD analysis. ...
... While providing detailed insights into airflow patterns and contaminant dispersion, CFD and other sophisticated modeling approaches impose substantial computational burdens; these methods typically require significant processing power and time to generate accurate results, making them impractical for continuous, real-time monitoring applications [66]. The computational intensity of these approaches becomes particularly problematic when scaling to large buildings or multiple facilities, as the resources required grow exponentially with the size and complexity of the monitored space [51]. Moreover, the need for specialized expertise to interpret and utilize these complex models adds another layer of operational overhead. ...
People spend a significant portion of their time in enclosed spaces, making indoor air quality (IAQ) a critical factor for health and productivity. Artificial intelligence (AI)-driven systems that monitor air quality in real-time and utilize historical data for accurate forecasting have emerged as effective solutions to this challenge. However, these systems often raise privacy concerns, as they may inadvertently expose sensitive information about occupants’ habits and presence. Addressing these privacy challenges is essential. This research comprehensively reviews the existing literature on traditional and AI-based IAQ management, focusing on privacy-preserving techniques. The analysis reveals that while significant progress has been made in IAQ monitoring, most systems prioritize accuracy at the expense of privacy. Existing approaches often fail to adequately address the risks associated with data collection and the implications for occupant privacy. Emerging AI-driven technologies, such as federated learning and edge computing, offer promising solutions by processing data locally and minimizing privacy risks. This research introduces a novel AI-based IAQ management platform incorporating the SITA (Spatial, Identity, Temporal, and Activity) model. By leveraging customizable privacy settings, the platform enables users to safeguard sensitive information while ensuring effective IAQ management. Integrating Internet of Things (IoT) sensor networks, edge computing, and advanced privacy-preserving technologies, the proposed system delivers a robust and scalable solution that protects both privacy and health.
... Over the past ten years, numerous studies have focused on computational fluid dynamics (CFD) modeling within the realm of urban physics, particularly addressing airflow and pollutant dispersion. Common benchmark scenarios typically involve airflow around individual buildings or clusters of structures with uniform or similar geometric shapes, simulating a simplified urban environment [14][15][16][17]. Research has extensively explored how the arrangement of objects influences flow patterns [18,19], pollutant dispersion [20,21], and urban ventilation [22,23] (Castro et al., 2017;Tong et al., 2016) within idealized city layouts characterized by regularly or irregularly positioned obstacles. ...
Urban traffic-related air pollution has emerged as a significant concern for the physical environment in densely populated urban areas. This study numerically investigates the dispersion of air pollutants and ventilation within typical urban blocks in Shanghai, considering the prevailing annual winds—northerly in winter (4.64 m/s) and easterly in summer (5.85 m/s). Multiple factors influence the dispersion of urban pollution. In this research, we examine the effects of viaducts and urban ventilation corridors, alongside the impact of urban parameters on pedestrian-level ventilation, by analyzing variations in building forms along residential streets in Shanghai. A novel approach for analyzing pollution dispersion is proposed, which involves performing a sensitivity analysis on the buffer radius and mapping various radii onto the C* parameter. The results indicate that: (1) enhancing air fluidity in regions with stagnant winds can be achieved by introducing vertical turbulence; (2) the prevailing wind direction, urban ventilation corridors, and urban permeability play a crucial role in determining the direction of pollutant dispersion at pedestrian levels in densely populated urban environments; (3) the contribution of pollutants released at ground level is significantly higher than those from viaducts at pedestrian height (248.58%). Drawing on both theoretical and experimental research, this study explores the spatial dispersion of air pollutants across various scales, including city-wide, block-level, and building-specific perspectives. The findings provide recommendations for the design of environmentally sustainable urban streets in residential areas.
... Over the years, numerous studies have characterized WDR exposure of building facades across various countries, primarily using semi-empirical approaches based on the so-called "WDR relationship" [7,[12][13][14][15][16]. Occasionally, the analysis of simultaneous DRWP complemented these characterizations, providing general benchmark indices for comparing exposures among different locations and establishing qualitative design requirements to mitigate rainwater intrusion on building facades [7,[17][18][19]. At the building scale, WDR and DRWP exposures vary significantly based on facade height and geometry, as well as the surrounding terrain, thereby altering the watertightness requirements for facades within the same location [20,21]. ...
Rainwater penetration into building facades results in multiple issues, including material and structural degradation, reduced energy efficiency, and health-related concerns among occupants. Currently, the watertightness performance of building facades is assessed based on standardized tests, which simulate generic water supplies and pressure differentials that do not reflect the specific exposure conditions of each facade. Consequently, practitioners’ decisions regarding facade design often rely on qualitative and imprecise criteria that do not align with the actual climatic loads. In this article, a comprehensive approach to facade design for preventing rainwater penetration is described, incorporating specific methodological refinements for reliable and practical implementation across various Spanish regions. In this approach, the parameters surpassed during any watertightness test (defined by the magnitude and duration of the water supplies and pressure differentials) are correlated with the recurrence of equivalent climatic exposures at the facade (determined by the climatic conditions of the site, facade height, and surrounding environment), thereby quantitatively characterizing the facade watertightness performance. The findings used to refine this method for implementation in Spain are illustrated and validated using selected case studies, and a comprehensive database is provided to enable its application at 360 locations distributed across various regions of the country.
... The findings presented here echo a commonly seen feature in RANS modeling given that across most of the hours both the standard k-ε model and the SST k-ω model underpredict the wind speed observed at the McTavish weather station. In wake regions such as the one at this station, RANS models are known to underestimate the TKE, which results in lower wind speeds [69]. The issue is exacerbated when the actual wind speed in the region is low, which was the case near the weather station across the hours simulated. ...
... Verification and validation studies are very important for increased confidence in CFD simulation results. Thus, it is a viable alternative to wind tunnel tests [78,79]. One of the main advantages of CFD simulations that makes them suitable for urban wind assessment applications is their ability to produce detailed visualisations and point measurements of different flow variables around and inside the studied urban configurations [58,71]. ...
... Since there should be a fine balance between the accuracy and the time needed for running the simulations, the investigation recommended the realizable k-ε RANS model for reaching this balance for urban wind flow problems. In that study, a variety of turbulence models were tested and the realizable k-ε yielded consistent results without taking a significant time to solve the flow [78]. ...
Due to the complex nature of the built environment, urban wind flow is unpredictable and characterised by high levels of turbulence and low mean wind speed. Yet, there is a potential for harnessing urban wind power by carefully integrating wind turbines within the built environment at the optimum locations. This requires a thorough investigation of wind resources to use the suitable wind turbine technology at the correct location—thus, the need for an accurate assessment of wind resources at the proposed site. This paper reviews the commonly used wind assessment tools for the urban wind flow to identify the optimum tool to be used prior to integrating wind turbines in urban areas. In situ measurements, wind tunnel tests, and CFD simulations are analysed and reviewed through their advantages and disadvantages in assessing urban wind flows. The literature shows that CFD simulations are favoured over other most commonly used tools because the tool is relatively easier to use, more efficient in comparing alternative design solutions, and can effectively communicate data visually. The paper concludes with recommendations on best practice guidelines for using CFD simulation in assessing the wind flow within the built environment and emphasises the importance of validating CFD simulation results by other available tools to avoid any associated uncertainties.
... Traditionally, urban microclimate analysis is performed based on observational methods (Toparlar et al., 2015). With the growing accessibility of computational resources, researchers have been utilizing numerical simulation methods (Blocken, Stathopoulos, Carmeliet, & Hensen, 2011). The main advantage of numerical simulations is the ability to generate various scenarios, referred to as comparative analyses (Blocken, 2015). ...
... Logarithmic law is assumed to describe the atmospheric boundary layer flow (ABL) at the inlet of CD; see Eq. (4) (Blocken, 2015;Blocken et al., 2011), where * friction velocity, the von Karman constant (0.42) and the height coordinate. The turbulent kinetic energy and the turbulence dissipation rate are given by Eqs. ...
... The environment is intrinsically associated with the occurrence and prevalence, influencing transmission pathways by affecting the dispersal of microorganisms or vectors [80,81]. Leveraging principles from fluid dynamics [82,83], ecological simulation methods are utilized to simulate the wind fields and water flows within the analysis area. By overlaying potential sources of infection, such as wet markets or landfills, it becomes possible to analyze the spatial spread range of pathogens or viruses, delineating multi-level impact areas. ...
The occurrence and spread of infectious diseases pose considerable challenges to public health. While the relationship between the built environment and the spread of infectious diseases is well-documented, there is a dearth of urban planning tools specifically designed for conducting Health Impact Assessments (HIAs) targeted at infectious diseases. To bridge this gap, this paper develops a comprehensive framework of an HIA for Urban Planning and Epidemic (HIA4UPE), formulated by considering the progression of public health incidents and the distinct transmission patterns of infectious diseases. This framework is designed to provide a comprehensive assessment by including a health risk-overlay assessment, health resource-quality assessment, health resource-equality assessment, and health outcome-impact prediction, enabling a multidimensional evaluation of the potential impacts of current environmental conditions or planning proposals on the incidence of infectious diseases. Furthermore, this paper advances the application of spatial analysis and computation, comprehensive assessment methodologies, and predictive analytics to conduct specific assessments. The theoretical framework and analytical tools presented in this paper contribute to the academic discourse and offer practical utility in urban planning and policymaking on epidemic prevention and control.
... It was ensured that no cells around important areas were larger than 1 m. The pedestrian level height (1.75 m) was divided by at least 0.5 m sized cells in height, as has been previously recommended [24,93]. On the other hand, geometric elements with details more intricate than 1 m and which may impact the wind flow were also divided using high resolution meshes. ...
(1) Background: Artificial intelligence (AI) and machine learning (ML) techniques are being more widely employed in the field of wind engineering. Nevertheless, there is a scarcity of research on the comfort of pedestrians in terms of wind conditions with respect to building design, particularly in historic sites. (2) Objectives: This research aims to evaluate ML- and computational fluid dynamics (CFD)-based pedestrian wind comfort (PWC) analysis outputs using a novel method that relies on the sophisticated handling of image data. The goal is to propose a novel assessment method to enhance the efficiency of AI models over different urban scenarios. (3) Methodology: The stages include the analysis of climate data, CFD analysis with OpenFOAM, ML analysis using Autodesk Forma, and comparisons of the CFD and ML results using a novel image similarity assessment method based on the SSIM, MSE, and PSNR metrics. (4) Conclusions: This study effectively demonstrates the considerable potential of utilizing ML as a supplementary tool for evaluating PWC. It maintains a high degree of accuracy and precision, allowing for rapid and effective assessments. The methodology for precise comparison of two visual outputs in the absence of numerical data allows for more objective and pertinent comparisons, as it eliminates any potential distortions. (5) Recommendations: Additional research can explore the integration of ML models with climate data and different case studies, thus expanding the scope of wind comfort studies.
... The selected meteorological conditions are guided by the geometry and the orientation of the building of interest (southwest-northeast direction), as shown in Figure 4. Thus, four different wind directions of the approaching flow were selected: along the length of (parallel to) the building (southwest and northeast winds), and perpendicular to the building (northwest and southeast winds). The last cases are of particular interest, as development of recirculation flows on the leeward side of buildings, trapping of pollutants, and elevated concentrations might be expected [57][58][59]. ...
The distribution of air pollutants in urban areas is significantly influenced by the presence of various geometric structures, including buildings, bridges, and tunnels. In built-up environments, meteorological conditions may influence the accumulation or dispersion of air pollutants in specific zones. This study examines the impact of wind and atmospheric stability on the dispersion of air pollutants around an apartment building situated in close proximity to a busy boulevard in a residential district of Sofia, Bulgaria. A series of dispersion simulations were conducted using the Graz Lagrangian Model (GRAL v.22.09) for a range of meteorological conditions, defined as combinations of the direction and velocity of the approaching flow, and of stability conditions within the study area of 1 × 1 km, with a horizontal resolution of 2 m. The resulting spatial distribution revealed the presence of hotspots and strong gradients in the concentration field. A simulation with meteorological data was also conducted, which was aligned with a campaign to monitor vehicular traffic. The sensitivity tests indicate that GRAL is capable of reproducing high-resolution pollutant fields, accounting for building effects at relatively low computational costs. This makes the model potentially attractive for city-wide simulations as well as for air pollution exposure estimation.
