Evaluation Schoolyard Wind Comfort Changes Due to Rapid Developments: Case Study of Nanjing, China

(1) Background: Evaluation of wind environments regarding pedestrian comfort may unveil potential hotspot areas, particularly in the context of the rapid urban development in China since the 1990s. (2) Method: With primary schools in Nanjing as case studies, the authors simulated the wind environment of schoolyards with the computational fluid dynamics (CFD) approach and evaluated relevant wind comfort criteria. (3) Results: The study showed that the comfortable wind environment of schoolyards generally expanded in three primary schools in summer and winter, and wind speed and the comfortable wind level decreased in some outdoor schoolyard spaces. The results also indicate that the mean wind speed of the schoolyards did not linearly correlate to the building density either within or outside the schools. An increase in the building height of the primary schools could improve the wind comfort of the schoolyard, but the increased building height in the vicinity may worsen the wind comfort in the schools. Meanwhile, a lift-up or step-shaped building design for schools can improve wind comfort in schoolyards. (4) Conclusions: This study provided simulated results and an approach for urban designers to evaluate and improve the wind environment for school children’s outdoor activities.

Impacts of building layout on pedestrian level wind comfort and gas pollutant diffusion

Introduction: The impacts of building layout on pedestrian level wind comfort and gas pollutant diffusion are simulated using computational fluid dynamics method. Materials and methods: The control equations of flow and pollutant diffusion are solved by using ANSYS Fluent. The SIMPLE algorithm is selected for the pressure-velocity coupling. The data from wind tunnel experiment at Tokyo Polytechnic University is employed in the validation case. Results: The velocity field and turbulence intensity at pedestrian level under different building layouts are obtained. The distribution and evaluation of wind comfort grade and pollutant concentration are given. Conclusion: Building layouts have significant impacts on flow and pollutant diffusion at pedestrian level. The outward staggered layout of building group can improve both wind comfort grade and air quality, but the inward staggered layout has the adverse effect. Non-staggered layouts are the worst in terms of the wind comfort grade in this paper.

Computational fluid dynamics as a method for studying wind comfort

The paper presents a comprehensive analysis of the wind flow interaction with a high-rise building, considering various types of streamlined flow acceleration, as well as an assessment of the aerodynamic shadow behind the building, and areas with increased wind speeds. The authors analyze risks caused by these zones, as well as suggest measures to minimize them.

Impact of volume distribution on pedestrian wind environment in high-rise urban districts: a CFD study

Pedestrian wind environment assessment is becoming an essential part of the urban design process especially in dense urban areas due to its ability to address the wind comfort/safety/health concerns in an early phase. In this paper, high-fidelity computational fluid dynamics (CFD) simulations, validated with experimental data, are performed on eight different designs in a generic urban layout to study the impact of volume distribution on pedestrian wind environment in high-rise urban districts. The results show that the blockage effects of the high-rise buildings decelerates the wind in the streets parallel to the flow while accelerating the flow in the streets perpendicular to the flow. This effect is evident up to a two block distance upstream of the high-rises. Furthermore, it is shown that consequent rows of high-rises in the downstream of the first row facing the wind flow have little effect on the upstream pedestrian wind; however, they have a significant role in the extent of affected areas downstream. The findings of this study provide further understanding about the impact of different volume distributions on pedestrian wind environment in high-rise urban districts and clarify their effect on wind safety and comfort.

The role of building morphology on pedestrian level comfort in Northern climate

Due to the rapid densification of cities, improving outdoor comfort is becoming increasingly important. To address this need, the current study introduces a methodology to evaluate outdoor comfort in the proximity of typical buildings in Tallinn, Estonia. The microclimate simulation software ENVI-met was employed to investigate the outdoor comfort conditions. The research outcomes show that the building's form, height, density, and orientation change consistently the pedestrian comfort around the buildings. The findings suggest that the integrated analysis of different building morphologies, massing, orientation, and their influences on the surrounding microclimate, thermal, and wind comfort are important.

THE IMPACT OF LEVEL OF DETAIL IN 3D CITY MODELS FOR CFD-BASED WIND FLOW SIMULATIONS

Climate change and urbanization rates are transforming urban environments, making the use of 3D city models in computational fluid dynamics (CFD) a fundamental ingredient to evaluate urban layouts before construction. However, current geometries used in CFD simulations tend to be built by CFD experts to test specific cases, most of the times oversimplifying their designs due to lack of information or in order to reduce complexity. In this work we explore what are the effects of oversimplifying geometries by comparing wind simulations of different level of detail geometries. We use semantic 3D city models automatically built and adjust them to their suitable use in CFD. For the first test, we explore wind simulations within a troublesome section of the TUDelft campus, the passage next to the EWI building (the tallest building in our domain), where the use of 3D city model variants show how differences in geometry and surface properties affect local wind conditions. Finally we analyze what these differences in velocity magnitude could mean for practitioners in terms of pedestrian wind comfort.

Harnessing the Power of the Cloud - Computational Fluid Dynamics With SimScale

Computational fluid dynamics is a computational method that enables engineers and designers to study the motion of fluids through computer simulations and modelling. Many tools on the market are so-called “in-house” tools requiring a certain level of expertise and upfront investment before proving their added value. Facilitated by the emergence of cloud computing, computer-aided engineering (CAE) technology is now offered as a software as a service (SaaS) solution, which increases its accessibility and ease of use. Online fluid flow (CFD) simulation is used in addressing a broad variety of problems like electronics design or pedestrian wind comfort (PWC), allowing engineers to accurately predict fluid flow behaviour guiding them towards smarter design decisions. SimScale is creating a paradigm shift for high-performance computing which can solve several problems that are faced when using on-premises software.