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Thesis Format

Integrated Article

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Supervisor

Savory, Eric

Abstract

The effects of the morphological model and the existence of an upstream tall building on the turbulent street canyon flow and the overlying boundary layer are investigated in a wind tunnel, using Stereoscopic Particle Image Velocimetry (S-PIV) measurements. The velocity variances, Reynolds shear stress, and turbulent kinetic energy are found to be larger than in a similar idealized street canyon model. Increasing building height results in a decrease in vertical mass fluxes across the opening of the canyon, at least in the canyon portion directly downstream of the building. The interaction between the large-scale structures in the overlying boundary layer and the small-scale structures in the street canyon is also investigated. The morphology does not impact the amplitude modulation mechanism of scale interaction, while an upstream building with a significantly larger height than the surroundings can greatly alter the scale interaction.

Summary for Lay Audience

Urban cities have their own unique climate, shaped by various factors such as wind, pollution, and temperature. These factors interact with the urban environment, creating what is known as the urban canopy. Understanding the urban canopy is vital for creating a comfortable and sustainable environment for city dwellers. Street canyons, which generally refer to a particular configuration of urban streets characterized by tall buildings or structures on either side, creating a narrow and enclosed canyon-like space, are very common in urban cities. To study the urban canopy, street canyons are usually modeled and studied through numerical simulations or wind tunnel experiments in a simplified format, which differs from the actual scenario. Therefore, it holds significance in understanding the behavior of turbulent flow within a realistic street canyon. The current study employs experimental techniques to evaluate the flow in a realistic street canyon downstream of a single upstream tall building of varying height, in a morphological model, in comparison with an idealized street canyon of the same aspect ratio in a homogeneous array of the same heights. Furthermore, to comprehend the influence of the flow in the boundary layer on the street canyon flow, the interaction between large-scale fluctuations in the overlying boundary layer and small-scale fluctuations at the roof-top level of the street canyon is also investigated. This work provides new insights into investigating the urban canopy of a realistic morphological model while also considering the influence of a local tall building.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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