2020/06/08 by Beatrice Pulvirenti, Silvana Di Sabatino, Pulvirenti, Beatrice +1
Engineering · Environmental Science · #Atmospheric and Oceanic Physics (physics.ao-ph) #Building Energy and Comfort Optimization #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Urban Heat Island Mitigation #Wind and Air Flow Studies
paper · pdf · doi:10.48550/arxiv.2006.04800
openalex publication_date 2020/06/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Heat exchange processes between building walls and external air within street\ncanyons is an important topic in air quality modelling considering that the\nthermal fields largely affect local flow dynamics and pollutant concentration\ndistribution. Despite the abundance of numerical studies, many questions still\nremain unanswered, ultimately limiting the inclusion of heat effects in\nmesocale atmospheric models. Of interest in this study is the assessment of\nradiative processes at building walls in terms of emissivity (i.e. is the ratio\nof the thermal radiation from a surface to the radiation from an ideal black\nsurface at the same temperature), shape factors (i.e. the proportion of the\nradiation which leaves the surface of a building and strikes toward the surface\nof another building) and their relation to the Richardson number. The study is\napproached via the computational fluid dynamics code OpenFOAM, with large eddy\nsimulations (LES) extension to model turbulence within the canyon and\nBoussinesq approach to model heat transfer. Consequences on pollutant\nconcentrations are also analysed. A model for setting the thermal boundary\nconditions on the building surfaces is developed, based on a database that\ngives the correlations between the emissivity of a surface and the heat flux\nemitted by this surface, under certain weather conditions, as a function of the\nlatitude and longitude of the surface, the orientation, the time of the day. As\na novel result an exponential law between the transfer coefficient and Ri (as\nwell as with the emissivity) is proposed as a function of the canyon aspect\nratio.\n