Confinement, boundaries and buoyancy in the mixing by fluid flows: towards an understanding of indoor air quality.

With the increasing urbanisation of society, human health & well-being is ever more affected by the air quality within our cities. We now spend over 90% of our time indoors and so the most chronic exposures can occur inside buildings. Mixing by buoyant fluid flows within buildings plays a dominant role in determining these exposures and the proposed research focuses on the buoyant turbulent plumes that arise in buildings from, the likes of, HVAC systems, window & door openings, radiators, electrical appliances, computers, cooking and the occupants themselves. An extensive campaign of laboratory experiments will examine the physics governing the mixing and transport of heat and tracers by turbulent buoyant plumes within the confining geometry of a room. Current exposure models take no account of the influence on the flow structure of the confinement of a room. The knowledge gained through this research will enable the development of models better suited to predicting indoor exposure levels, thereby enabling better management of exposure. Investigation of these flows also has considerably broader relevance and future application to examine include, for example, the mixing and dilution of flows within our urban environments, the mixing of fluids in the food, beverage & pharmaceutical industries, and the pollutant and nutrient transport in the Earth's oceans.

This work will investigate factors which affect the mixing by fluid flows typical of the flows within building, specifically by: 1) De-coupling the effects of confinement from those of the no-slip condition which are typically simultaneously introduced into a fluid flow by the presence of a boundary - this is of fundamental scientific interest; 2) Varying the extent of the confinement imposed on the flow by the introduction of a jointed wall so that the degree of confinement can be continuously varied. The jointed wall can mimic the confinement of a corner formed by the meeting of two walls within a room. The angle of this corner wall can then be systematically varied to replicate the confinement imposed when, for example, people or computer equipment are placed, for example, near a corner within a room, next to a plane wall, or indeed near an obtuse 'external' corner. The new understanding will enable better modelling of the mixing produced by heat sources, including people, radiators and computers, within rooms - providing a practical output of real application and value to society.

Improved understanding of mixing in the presence of boundaries and confinement will have a crucial impact on our comprehension and management of air quality both within buildings and within the wider urban environment. Select industrial partners, e.g. Foster+Partners, Dyson Technology Ltd, and Arup, have been made aware of the intended research and support this being carried out in an academic institution with strong links to industrial application. Moreover, they are keen to work with Dr Burridge to develop tangible impacts from the research, in terms of products, practises and guidance. Publications in international journals and presentation at international conferences will be used to support dissemination of project aims, opportunities and outputs. Impact activities that address these issues, along will details of impact and planned actions to attain impact, are presented under the headings of Knowledge, People, Economy and Society.

Knowledge: The research will develop new understanding and mathematical models that will have application to specific issues from the air quality and human comfort in buildings, pollutant dispersion in urban environments, to the fate of nutrients within lakes and oceans.
Action: Results will be published in respected and highly visible journals (e.g. the journal J. Fluid Mech., Building and Environment, etc...) and presented at international meetings (e.g. APS DFD meetings, Indoor Air meetings). All data and models will be made publicly available through open-innovation access in compliance with EPSRC Open Data policy. The UK Fluids Networks (with access to over 500 PIs) and a number of its Special Interest Groups will be utilised to disseminate the findings and their implication.

People: This project will provide training for an PDRA and will link to ongoing & planned MEng and PhD student projects. The PDRA and linked students will benefit from links to the UK Fluids Network and industrial partners working with Dr Burridge
Action: The PDRA and linked students will attend departmental and university-wide seminars, and will be encourage to the wide range of activities ongoing in the laboratory.

Economy: The urban environment and the activities within its buildings is a critical part of any developed economy, especially that of the UKs. Carbon emissions from the built environment are substantial with buildings contributing ~30% of UK carbon emissions, a significant fraction of which is due to heating and cooling. Understanding how the ventilating and heating flows within buildings interact with the walls and floors, is to understand how air flows interact with the very fabric of our buildings. Furthermore, improved indoor air quality is being increasingly recognised by companies as a viable route to improve productivity whilst improving employee health & well-being. Better understanding of the interaction between ventilating flows and buildings will enable better prediction and control of indoor air quality.
Action: Dr Burridge has already interested 3 industrial partners in the findings from this research and through his leadership of the Low-Energy Ventilation Network Dr Burridge has strong links with 12 industrial partners, practising various aspects of building ventilation.

Society: Better ventilation of our buildings is a contributing factor in efforts to live sustainably on this planet. Better ventilation lowers energy consumption in buildings, uses energy more efficiently, improves indoor air quality and reduces pollution by emissions. As such, it impacts on the whole of society.
Action: Dr Burridge, the PDRA and linked students will be encouraged to take part in outreach events at all levels to communicate the direct and indirect benefits being realised by the specific and connected research projects. Where appropriate, Dr Burridge will use his experience of working with the local and national media to communicate their findings and leverage the impact.