A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Non-isothermal flow between heated building models
Abstract The Urban Heat Island Effect describes the phenomenon that urban areas are typically warmer than the nearby rural areas, as the presence of the city causes an increase in air temperature. Increased temperatures in urban environments lead to increased discomfort, health problems, and higher cooling demands. It is therefore essential to be able to predict the location where higher temperatures tend to occur and to propose mitigation strategies for such local hot-spots. In this study, we present flowfield and temperature measurements from the ETHZ/Empa Atmospheric Boundary Layer wind tunnel. Time-averaged Particle Image Velocimetry is used to examine the non-isothermal flow in two geometric configurations of a three-dimensional street canyon surrounded by a realistic city geometry. We investigate the effect of buoyancy by measuring at forced to mixed convection flow regimes with Richardson (Ri) numbers ranging from 0 to 1.09. The work differs from previous studies, in that a finite-length street canyon with heated surfaces is considered. This set-up results in an increasing flow rate that escapes the street canyon volume as the flow becomes increasingly buoyancy-driven. Turbulent kinetic energy (TKE) levels increase with increasing Ri as flow exiting the street canyon mixes with the freestream flow.
Highlights Wind tunnel measurements are performed in a scaled-down street canyon with heated surfaces. Weaker recirculation is seen for non-isothermal conditions; the street canyon vortex breaks up at high surface temperatures. In the step-down geometry, air is removed from the control area at a higher rate compared to the step-up configuration. Air temperature measurements show lower average temperatures in the street canyon for the step-down configuration.
Non-isothermal flow between heated building models
Abstract The Urban Heat Island Effect describes the phenomenon that urban areas are typically warmer than the nearby rural areas, as the presence of the city causes an increase in air temperature. Increased temperatures in urban environments lead to increased discomfort, health problems, and higher cooling demands. It is therefore essential to be able to predict the location where higher temperatures tend to occur and to propose mitigation strategies for such local hot-spots. In this study, we present flowfield and temperature measurements from the ETHZ/Empa Atmospheric Boundary Layer wind tunnel. Time-averaged Particle Image Velocimetry is used to examine the non-isothermal flow in two geometric configurations of a three-dimensional street canyon surrounded by a realistic city geometry. We investigate the effect of buoyancy by measuring at forced to mixed convection flow regimes with Richardson (Ri) numbers ranging from 0 to 1.09. The work differs from previous studies, in that a finite-length street canyon with heated surfaces is considered. This set-up results in an increasing flow rate that escapes the street canyon volume as the flow becomes increasingly buoyancy-driven. Turbulent kinetic energy (TKE) levels increase with increasing Ri as flow exiting the street canyon mixes with the freestream flow.
Highlights Wind tunnel measurements are performed in a scaled-down street canyon with heated surfaces. Weaker recirculation is seen for non-isothermal conditions; the street canyon vortex breaks up at high surface temperatures. In the step-down geometry, air is removed from the control area at a higher rate compared to the step-up configuration. Air temperature measurements show lower average temperatures in the street canyon for the step-down configuration.
Non-isothermal flow between heated building models
Tsalicoglou, C. (author) / Allegrini, J. (author) / Carmeliet, J. (author)
2020-05-21
Article (Journal)
Electronic Resource
English
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