Simulating Urban Air Pollution In The Lab

There has been increased evidence in recent years about the health risks of air pollution, which contribute to millions of deaths globally and tens of thousands of UK deaths annually. This research is about improving our ability to model urban air pollution and wind patterns to inform policy affecting people's health and wellbeing. These scientific advances will be achieved by applying advanced aerospace approaches including scale-model aerodynamic testing, in-situ measurements in real-life buildings, and data-driven methods coupling measurements to computational fluid dynamics models. These novel approaches promise to reveal understanding of the dispersion and transport of pollutants from industrial and urban sources and advance our ability to monitor, model, and control airborne pollution at the local and city scales critical for urban flows. These techniques allow us to fill a gap in our knowledge about the influence of local flow patterns to pedestrian comfort, building optimisation, air quality, and macroscale weather prediction.

The scale-model aerodynamics experiments will focus on using state-of-the-art optical diagnostic tools to reveal the wind patterns that are the mechanisms of pollution dispersion in and around building models. In the first part of this fellowship, novel experiments were developed using scale models in a recirculating water tunnel with dye as a proxy for air pollution. These experiments successfully replicated atmospheric boundary layer conditions and highlighted the importance of tall buildings in enhancing vertical transport of ground-level pollution out of the urban canopy. In this extension, particle tracking techniques and transparent city models will be employed to reveal the dynamics of the flow features at street level and within urban canyons.

The lab measurements will be supplemented by in-situ measurements of real-life buildings. This is made possible by an interdisciplinary collaboration using University of Southampton campus buildings. These measurements will be an opportunity to validate models and will feed into the new data-driven approaches that will be used to analyse the results and translate them into industry impact.

Data-driven methods aim to reduce the complexity of the turbulent flow models, fill in missing information, and reveal physics of the flow. Urban aerodynamics provides a novel application well-suited to this approach as key flow features are expected to be anchored by the terrain and novel as both velocity and concentration properties of the flow need to be captured in the physics.

Impact to industry will continue to be fostered by working closely with the wind engineering community. Impact to policy will continue to be supported through case studies simulating air pollution in the city of Southampton and contributing to national strategy documents. The public outreach made possible through this fellowship also highlights that aerodynamics is not only relevant to aeroplanes and race cars and that a diversity of people can work in this field, showcasing "urban aerodynamics" as an emerging field of research.

This fellowship extension is an opportunity to build on these foundations to broaden the inter-disciplinary applicability of the new science we uncover and translate the results into further policy-relevant and industry-relevant impact.