Bioclimatic Reformation of Urban Area - A CFD Study

Computational Fluid Dynamic (CFD) analysis with the method of finite volume is used in order to study the improvement of microclimate in an urban agglomeration in the city of Volos, in the frame of bioclimatic reformations. For the modeling of the thermal buoyancy the Boussinesq approximation is used, while for the radiation is used the Discrete Ordinate (DO) model with two wave length bands. The ground temperature is determined, solving an energy balance model according to the covering materials' properties, while it is considered infrared diffusive radiation emitter. The planted surfaces are assumed as finite thickness heat sinks. Roofs and buildings walls are also assumed as finite thickness isothermal walls and sources of heat corresponding to the heat pumps and electrical devices' operation as well as to the users' occupancy. Trees are porous volumes adding source and sink terms to the momentum, turbulence and energy equations and causing shading while the surfaces of water elements are considered isothermal walls and heat sink, at the same time. The local microclimate before and after the bioclimatic interventions are presented in terms of temperature and wind speed distribution. The effect of the examined reformation is assessed through parametric studies in terms of thermal comfort indices. Parametric studies concerns cool ground covering materials, green cover, shading layout, and buildings' thermal emissions.