Imperial College London


Faculty of Natural SciencesCentre for Environmental Policy

Research Fellow in Air Pollution Policy







307Weeks BuildingSouth Kensington Campus





Publication Type

8 results found

Woodward H, Schroeder A, Le Cornec C, Stettler M, ApSimon H, Robins A, Pain C, Linden Pet al., 2022, High resolution modelling of traffic emissions using the large eddy simulation code Fluidity, Atmosphere, Vol: 13, ISSN: 2073-4433

The large eddy simulation (LES) code Fluidity was used to simulate the dispersion of NOx traffic emissions along a road in London. The traffic emissions were represented by moving volume sources, one for each vehicle, with time-varying emission rates. Traffic modelling software was used to generate the vehicle movement, while an instantaneous emissions model was used to calculate the NOx emissions at 1 s intervals. The traffic emissions were also modelled as a constant volume source along the length of the road for comparison. A validation of Fluidity against wind tunnel measurements is presented before a qualitative comparison of the LES concentrations with measured roadside concentrations. Fluidity showed an acceptable comparison with the wind tunnel data for velocities and turbulence intensities. The in-canyon tracer concentrations were found to be significantly different between the wind tunnel and Fluidity. This difference was explained by the very high sensitivity of the in-canyon tracer concentrations to the precise release location. Despite this, the comparison showed that Fluidity was able to provide a realistic representation of roadside concentration variations at high temporal resolution, which is not achieved when traffic emissions are modelled as a constant volume source or by Gaussian plume models.

Journal article

de Kreij RJB, Wykes MSD, Woodward H, Linden PFet al., 2022, Modeling disease transmission in a train carriage using a simple 1D-model, INDOOR AIR, Vol: 32, ISSN: 0905-6947

Journal article

Collins CM, Otero A, Woodward H, 2022, Shape matters: reducing people’s exposure to poor air quality using sculpted infrastructure elements, Cities & Health, Vol: 6, Pages: 1-7, ISSN: 2374-8834

Air pollution in cities disproportionately affects children and those living in economically-deprived areas near busy roadways. Walls are effective in deflecting particulate matter but the addition of shaping either at the design stage, or as retrofit, improves performance. High-wall baffles reduce distal vortex accumulations; On pavements, low-level baffles can deflect suspended particulates back towards the road surface. These shaped structures can scaffold urban plantings and, in tandem, improve the effectiveness of urban green in this context. Shaped baffles are immediately effective, inexpensive and create a win-win that engages stakeholders. This awareness will drive collaborations between planners, designers and modellers for effective and beautiful street furniture elements that reduce pollution exposure.

Journal article

Burridge HC, Bhagat RK, Stettler MEJ, Kumar P, De Mel I, Demis P, Hart A, Johnson-Llambias Y, King M-F, Klymenko O, McMillan A, Morawiecki P, Pennington T, Short M, Sykes D, Trinh PH, Wilson SK, Wong C, Wragg H, Davies Wykes MS, Iddon C, Woods AW, Mingotti N, Bhamidipati N, Woodward H, Beggs C, Davies H, Fitzgerald S, Pain C, Linden PFet al., 2021, The ventilation of buildings and other mitigating measures for COVID-19: a focus on wintertime, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol: 477, Pages: 1-31, ISSN: 1364-5021

The year 2020 has seen the emergence of a global pandemic as a result of the disease COVID-19. This report reviews knowledge of the transmission of COVID-19 indoors, examines the evidence for mitigating measures, and considers the implications for wintertime with a focus on ventilation.

Journal article

Corada K, Woodward H, Alaraj H, Collins CM, de Nazelle Aet al., 2021, A systematic review of the leaf traits considered to contribute to removal of airborne particulate matter pollution in urban areas, Environmental Pollution, Vol: 269, Pages: 1-13, ISSN: 0269-7491

Global urban planning has promoted green infrastructure (GI) such as street trees, shrubs or other greenspace in order to mitigate air pollution. Although considerable attention has been paid to understanding particulate matter (PM) deposition on GI, there has been little focus on identifying which leaf traits might maximise airborne PM removal. This paper examines existing literature to synthesize the state of knowledge on leaf traits most relevant to PM removal. We systematically reviewed measurement studies that evaluated particulate matter accumulated on leaves on street trees, shrubs green roofs, and green walls, for a variety of leaf traits. Our final selection included 62 papers, most from field studies and a handful from wind tunnel studies. The following were variously promoted as useful traits: coniferous needle leaves; small, rough and textured broadleaves; lanceolate and ovate shapes; waxy coatings, and high-density trichomes. Consideration of these leaf traits, many of which are also associated with drought tolerance, may help to maximise PM capture. Although effective leaf traits were identified, there is no strong or consistent evidence to identify which is the most influential leaf trait in capturing PM. The diversity in sampling methods, wide comparison groups and lack of background PM concentration measures in many studies limited our ability to synthesize results. We found that several ancillary factors contribute to variations in the accumulation of PM on leaves, thus cannot recommend that selection of urban planting species be based primarily on leaf traits. Further research into the vegetation structural features and standardization of the method to measure PM on leaves is needed.

Journal article

Woodward H, Stettler M, Pavlidis D, Aristodemou E, ApSimon H, Pain Cet al., 2019, A large eddy simulation of the dispersion of traffic emissions by moving vehicles at an intersection, Atmospheric Environment, Vol: 215, Pages: 1-16, ISSN: 1352-2310

Traffic induced flow within urban areas can have a significant effect on pollution dispersion, particularly for traffic emissions. Traffic movement results in increased turbulence within the street and the dispersion of pollutants by vehicles as they move through the street. In order to accurately model urban air quality and perform meaningful exposure analysis at the microscale, these effects cannot be ignored. In this paper we introduce a method to simulate traffic induced dispersion at high resolution. The computational fluid dynamics software, Fluidity, is used to model the moving vehicles through a domain consisting of an idealised intersection. A multi-fluid method is used where vehicles are represented as a second fluid which displaces the air as it moves through the domain. The vehicle model is coupled with an instantaneous emissions model which calculates the emission rate of each vehicle at each time step. A comparison is made with a second Fluidity model which simulates the traffic emissions as a line source and does not include moving vehicles. The method is used to demonstrate how moving vehicles can have a significant effect on street level concentration fields and how large vehicles such as buses can also cause acute high concentration events at the roadside which can contribute significantly to overall exposure.

Journal article

Woodward WH, Utyuzhnikov S, Massin P, 2018, Developments of the method of difference potentials for linear elastic fracture mechanics problems, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Vol: 115, Pages: 75-98, ISSN: 0029-5981

Journal article

Song J, Fan S, Lin W, Mottet L, Woodward H, Wykes MD, Arcucci R, Xiao D, Debay J-E, ApSimon H, Aristodemou E, Birch D, Carpentieri M, Fang F, Herzog M, Hunt GR, Jones RL, Pain C, Pavlidis D, Robins AG, Short CA, Linden PFet al., 2018, Natural ventilation in cities: the implications of fluid mechanics, BUILDING RESEARCH AND INFORMATION, Vol: 46, Pages: 809-828, ISSN: 0961-3218

Journal article

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