Measuring a pollutant plume over a 3D printed city model

The modelling of urban air pollution requires an understanding of the turbulent processes involved. This projects aims to provide direct measurements of turbulent dispersion over urban terrain with a high-fidelity experimental study. An investigation into scalar dispersion over a 3D-printed model of the City of Southampton, which is a medium-size coastal city in the south of England, was carried out. This 1000:1 scale model was created to represent 1 km2 of Southampton’s city centre experiencing an onshore south-south-westerly wind. Experimentally measuring turbulent scalar fluxes is challenging as it requires both concentration and velocity measurements in the same place, and at the same time. Particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) were used to measure full fields of these turbulent scalar fluxes. Measurements were carried out in streamwise-vertical and wall-parallel planes to create a detailed map of concentration and velocity data for a case in which a plume from an offshore point source was introduced upstream of this model.