Dispersion modelling provides a mathematical simulation that demonstrates how pollutants disperse through the air. These types of models are relevant as they are often used to help inform important urban development, emergency management and policy decisions. As part of the MAGIC project, Researcher, Elsa Aristodemou, has been investigating how tall buildings may influence the outputs of these dispersion models. A summary of her research so far is illustrated through the three below animations.
The animation shows the tracer dispersion (and trapping) within the same vertical plane (X-Z) through the centre of the computational domain (same as in the first animation). The source of the tracer emission is at the top of the central building. The animation shows how the dispersion is affected by the increased height of the buildings surrounding the source building (which remained at original height). The height of the tallest building (left of the source) corresponds to 120m in real life, whilst the tall building downstream of the source-building is ~ 80m high. It's interesting to see how the pollution in this scenario effectively "oscillates" at a "fixed" height between the two buildings, but some of it is also transported around the downstream/left tall building, due to velocity field (see animation 1 and the velocity field generated).
Animation 3 - Tracer Dispersion- Normal buildings scenario (E. Aristodemou, LSBU/ICL, 2017).
The animation shows the velocity field in a vertical (X-Z) plane through the centre of the computational domain which comprises a 7-building configuration. The simulation results were obtained using the Large Eddy Simulation (LES) within the FLUIDITY software. The inlet velocity boundary is a turbulent velocity inlet on the left of the domain, with the turbulence being generated by the synthetic eddy method (Jarrin, 2006). The effect of the first tallest (thin) building (~ 120m in real life) is clearly seen downstream of the domain. The second tallest building on the right corresponds to ~ 80m in real life.
Animation 2 - Tracer Dispersion- Tall buildings scenario (E. Aristodemou, LSBU/ICL, 2017).
Animation 1 - Velocity field- Tall Building Scenario (E. Aristodemou, LSBU/ICL, 2017).
The animation shows how the dispersion of the tracer in the same (X-Z) plane when the building heights are "normal" (maximum heights not exceeding 30m in real life). The tracer is transported a long away downstream of the buildings, but also a considerable amount is "trapped" in the lower levels between the source-building and the building downstream.
The ultimate aim of this project is to find a cost-beneficial method in which to change the way our cities are developing. The Victorians improved health by covering sewage systems- let's see if we can do the same by improving air quality.
This project encompases a transdisciplinary research group from the Universities of Cambridge, Surrey and ICL, but we know that innovations take place beyond our reach, therefore we want to work with other academics and industry partners to further our work.
We want to inform decision makers to ensure the results of this project can benefit cities across the globe, therefore we are excited to share all elements of our research to ensure the sustainable development of cities for the future.