On the Assessment of Wind Microclimate in a Complex Urban Environment Utilising Computational Fluid Dynamics

This paper presents an insight and key considerations for using Computation Fluid Dynamics (CFD) to simulate the Wind Microclimate in a Complex Urban Environment. The current study involved developing a local 10m height “reference” wind rose for the project site and then combining statistical meteorological data with aerodynamic information and wind comfort and wind safety criteria. Where wind speeds were found to be at undesirable wind levels at areas of interest (ground level, podium level, terraces, balconies, etc.), recommendations were made to reduce detrimental wind effects, e.g. using landscaping, porous windbreaks, canopies, etc. The criteria used in the evaluation of pedestrian-level winds surrounding the proposed development were based on the well-established “Lawson” criteria which couple the probability of exceeding winds at given statistical levels with wind speed magnitudes originally related to the Beaufort Land Scale. To take into account the influence of the immediate surrounding environment, all neighboring buildings and local topography within a diameter of almost 1,000 m around the site were included in the developed CFD model. Furthermore, all small canopies, balconies, and semi-open spaces were modeled in detail as per the provided architectural drawings. Based on a mesh sensitivity assessment, polyhedral elements were used for the entire computational domain. CFD analysis offers a comprehensive range of output including the velocity distribution in three directions and turbulence levels, allowing the identification of hot spot areas that have potentially unacceptable wind conditions for further assessment and mitigation treatments to reduce wind speed to acceptable levels. The baseline (no mitigation) scenario simulation results contributed to a better understanding of the environmental wind impact for the project at the site, enabling a targeted approach to the development of effective windbreak options This paper provides a comprehensive approach toward the establishment of a robust CFD assessment of human comfort to ensure that proposed building developments and their streetscapes create a comfortable wind environment to live and visit.