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Proceedings of BSO Conference 2016: Third Conference of IBPSA-England

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Three-Dimensional High-Resolution Urban Thermal & Mechanical Large Eddy Simulation Interactive Physics Between Buildings, Land Cover And Trees

Mohammed Bakkali, Atsushi Inagaki, Yasunobu Ashie, Manabu kanda, Mike Davies, Philip Steadman, Siegfried Raasch

Abstract: The large eddy simulation (LES) model ‘PALM’ was further developed for the computation of irregular turbulent vertical transports within real urban environments counting buoyancy-driven flows. The model was implemented with calculated initial boundary conditions for three-dimensional highresolution heterogeneous sensible heat fluxes from buildings, tree crowns and different land use categories. These fluxes were initially computed by a multi-patch urban energy balance model (3D City Irradiance). The results were then inserted into the LES model through Neumann boundary conditions. Such detailed thermal effects in urban LES were not previously investigated. Results from this research showed that heterogeneous distribution of sensible heat fluxes at the wall surface led to more localised convections within the surface layer and above. This new numerical method aims at enhancing the capabilities of mathematical models for predicting extreme weather hazards stressed by urban environments such as overheating and turbulent mixing above the urban surface. The method was based on a binary approach grounded on aerodynamics and thermodynamics. More accurate estimates of maximum temperatures, their time of occurrence and their detailed spatial distributions are estimated. Two locations in Nagoya and Tajimi City in Japan were used for case studies by considering the effects of improved evaporation efficiency in building construction materials.
Pages: 338 - 345
Paper:
bso2016_1022