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Managing Air for Green Inner Cities (MAGIC)

Managing Air for Green Inner Cities (MAGIC)

Project Overview

MAGIC is an ESPRC-funded Grand Challenge research project that aims to address the question "How to develop cities with no air pollution and no heat-island effect by 2050?"

An increasing portion of the UK population live in urban areas, where exposure to air pollution and heat stress is significantly elevated. Poor air quality in particular is strongly linked with a number of health issues, including asthma and cardiovascular disease, costing the National Health Service millions of pounds each year.

A large part of the problem is traditional heating, ventilation and air conditioning (HVAC) systems used inside urban buildings, which are typically very energy-consuming and thus responsible for significant amounts of urban air pollution. They also raise the external temperature, which drives a higher demand for the use of HVACs, increasing temperature and emissions further. MAGIC aims to break this vicious cycle by developing a system in which the city air is managed to become its own 'natural HVAC' system. This will be done using natural ventilation in buildings, increased albedo, plus green (parks) and blue (water) spaces.

To achieve this aim, MAGIC will establish a suite of models that cover a range of functions/complexities. A high-resolution computational fluid dynamic (CFD) model will be used to provide detailed simulations of urban airflow on the building to neighbourhood scale, including a coupling of external and internal flows in naturally ventilated buildings. Reduced-order and cost-benefit models will also be developed for operational planning and optimisation.

Wind-tunnel, laboratory, and monitoring studies will also be undertaken to increase process understanding and provide means by which to validate the computational studies. Suitable case study sites have already been identified for monitoring deployment, including the area around Marylebone Road, London, originally used for the DAPPLE project (www.dapple.org.uk) (Fig.1).

Figure 1

Fig.1: Satellite view of the DAPPLE field site. Imagery ©2016 Google, Map data ©2016 Google.

Our Role

Within the Department of Geography, initial work will focus on further development of the multi-scale atmospheric model ATHAM-Fluidity, the state-of-the-art large-eddy simulation (LES) CFD model to be used for MAGIC, towards simulating airflow, dispersion and temperatures within an urban setting.

ATHAM-Fluidity is a new open-source model borne from previous collaborations between the University's atmospheric process group and the Applied Modelling and Computation Group (ACMG) at Imperial College London (ICL). It combines the dynamical core of Fluidity, which enables dynamic grid mesh adaption, with the Active Tracer High-Resolution Atmospheric Model (ATHAM), which contains parameterisations relevant to many atmospheric processes (Fig.2). The scalability and mesh adaption capabilities of ATHAM-Fluidity make it a powerful tool for simulating atmospheric flows over large but complex geometries such as cities.

Key areas of development of ATHAM-Fluidity relevant to MAGIC include:

  • An improved representation of surface fluxes over heterogeneous urban environments that will include built-up areas as well as green (parks) and blue (water) spaces.
  • A chemistry scheme capable of modelling reactions between the most relevant urban pollutants (e.g. ozone and nitrogen oxides).
  • A radiation scheme capable of modelling 3-D effects due to, e.g., building shading and clouds.
  • Integration of aggregated emissions data to be used as input to the model.
  • The ability to use arbitrary as well as idealised initial/boundary profiles.
  • Improvements to other parameterisations such as the subgrid turbulence and cloud microphysical schemes.

Figure 2

Fig.2: ATHAM-Fluidity simulation of a rising warm bubble, showing the mesh-adaptive capabilities of the model (right). Figure taken from Savre et al. (2016).

People

The following people in the Department are directly involved in the MAGIC project:

Much of the initial development of ATHAM-Fluidity has been carried out by Dr Julien Savre, who remains in the Department.

Collaborators

MAGIC is an interdisciplinary project involving a number of other University Departments (DAMTP, Department of Engineering, Department of Chemistry, Department of Architecture), as well as other UK institutions (Imperial College London, University of Surrey).

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