Showing papers by "Silvana Di Sabatino published in 2013"
TL;DR: In this article, the authors reviewed recent findings in the field of flow and pollutant dispersion modelling around buildings and within complex urban geometries, showing that complexity is not only associated to the packing density of buildings, but originates also from building-height variability, buoyancy effects close to the building walls, traffic-produced turbulence and from the presence of vegetation.
Abstract: This paper reviews recent findings in the field of flow and pollutant dispersion modelling around buildings and within complex urban geometries Complexity is not only associated to the packing density of buildings, but originates also from building-height variability, buoyancy effects close to the building walls, traffic-produced turbulence and from the presence of vegetation Recent results are discussed in light of progress made in operational urban dispersion models as a way forward for the application of those models in real scenarios
78 citations
TL;DR: In this article, a field experiment, dubbed transition flow experiment, was conducted in Phoenix, Arizona to study the evening transition in complex terrain (shift of winds from upslope to downslope) and two scenarios were considered: (i) the flow reversal due to a change of buoyancy of a cooled slab of air near the ground, and (ii) the formation of a transition front.
Abstract: Motivated by air quality and numerical modelling applications as well as recent theoretical advancements in the topic, a field experiment, dubbed transition flow experiment, was conducted in Phoenix, Arizona to study the evening transition in complex terrain (shift of winds from upslope to downslope). Two scenarios were considered: (i) the flow reversal due to a change of buoyancy of a cooled slab of air near the ground, and (ii) the formation of a transition front. A suite of in-situ flow, turbulence and particulate matter (PM) concentration sensors, vertically profiling tethered balloons and remote sensors were deployed, and a mesoscale numerical model provided guidance for interpreting observations. The results were consistent with the front formation mechanism, where it was also found that enhanced turbulence associated with the front increases the local PM concentration. During the transition period the flow adjustment was complex, involving the arrival of multiple fronts from different slopes, directional shear between fronts and episodic turbulent mixing events. The upward momentum diffusion from the incipient downslope flow was small because of stable stratification near the ground, and full establishment of downslope flow occurred over several hours following sunset. Episodic frontal events pose challenges to the modelling of the evening transition in complex terrain, requiring conditional parametrizations for subgrid scales. The observed increase of PM concentration during the evening transition has significant implications for the regulatory enforcement of PM standards for the area.
36 citations