One of our Raspberry- Pi Cameras used on site

Video shows the water bath experiment as viewed from the side

Envisaging a world with greener cities.

WIND TUNNEL:

In the video opposite, Will explains his work recreating the London test site in the Enflo  wind tunnel at the University of Surrey. Will is now building a scaled-down replica of our Cambridge test site for the next phase of wind-tunnel experiments, and he has already created a drawing of each of the 167 model buildings.

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LONDON TEST SITE:

In September this year we ran a 2-week intensive field study at London Road next to London South Bank University (LSBU). Our aim for this study was to collect data for calibration and validation of the different MAGIC models.

Originally, the idea was to replicate the 2017 study which involved various low-cost sensors developed by the MAGIC project. In 2017 these sensors were based along a stretch of London Road just South of St Georges Circus and also inside a room in the LSBU Clarence Centre. This time we decided to also add a camera to obtain traffic information with the hope to be able to determine the effect of traffic on pollution levels.

As planning progressed, we were lucky to have TfL join us. TfL agreed to change the signal timings at the Garden Row/London Road junction to see whether doubling the cycle time would lead to a decrease in emissions. It became clear very quickly that we would need high precision and high time resolution sensors to really be able to understand the effects of the changes in signal timings. As these high cost sensors are quite power intensive and supposed to be run indoors on mains power, we had to design various bespoke battery systems to power these instruments and find boxes to protect the sensors against rain.

We relied heavily on the help and support of the team at LSBU, including the security staff and lab technicians who enabled us to move and store our equipment safely, and Elsa Aristodemou, MAGIC PI, who coordinated the LSBU team. Thank you for all your help!

To ready more about the study click here. 

THE WATER FLUME:

Megan and her team have been carrying out experiments investigating the effect of temperature differences on cross-ventilation. The experiments are performed in a large flume, with a cross-sectional area of 2 m x 1 m. Into the flume is placed a model room, which is a 0.5 m cube.

Before the start of an experiment, the water inside the model room is heated and dyed. The flume is switched on, to provide a flow past the model room, modelling the effect of wind. Two windows are opened on opposite walls of the model room, one at the front, facing the wind, and one at the back. 

Recent experiments have examined the effect of temperature on cross-ventilation. Results show that the major effect of the initial temperature difference between the room and ambient is to create a two-layer stratification, reducing the effective volume of the room. New theory indicates that the temperature difference does not significantly impact the ventilation flow rate through the windows, but the change in effective room volume alters the timescale over which the room is ventilated. These results are currently being written up for publication. You can read a summary of the findings here. 

Experiments performed by Megan Davies Wykes and Elkhansaa Chahour.

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