Cameron Southgate-Ash

Phase I - A series of wind tunnel experiments will be designed and carried out to assess the turbulence structure over urban morphologies, characterized by tall buildings of uniform height and a packing density that is typical of megacity environments. These will be performed in the ‘A’ wind tunnel at the University of Surrey. The level of details characterising the model of the buildings will be progressively increased, to produce a multi-scale roughness. The turbulence structure developed over single- and multi-scale roughness will be compared to assess similarities/differences. Scaling laws based on the characteristic length scales of the morphologies will be explored. For all cases, the drag generated by the morphologies will be measured by instrumenting a building with static pressure ports on all faces. This drastically reduces the uncertainty inherent in the law of the wall in rough wall turbulent boundary layers. To incorporate the effect of spatially heterogeneous surfaces, several velocity profiles will be collected with Laser Doppler Anemometry (LDA) to allow for analysis of spatially averaged quantities.

Phase II - The effect of ABL stratification will be examined in the unique ‘EnFlo’ wind tunnel (NERC National facility) at the University of Surrey. Similar single- and multi-scale urban roughness will be investigated (via LDA). Concentration measurements via Fast-response Flame Ionisation Detector (FFID) are also planned to complement the velocity profiles, and inform the urban dispersion phenomenon as a function of both the atmospheric stability and buildings length scales.