Abstract
Rapid urban growth and development over the past few years in Dubai has increased the rate at which the mean maximum temperatures are rising. Progressive soaring temperatures have greater effect of heat islands that add on to the high cooling demands. This work numerically explicated the effect of HIs in a tropical desert climate by adopting Heriot-Watt University Dubai Campus (HWUDC) as a case study. The study analysed thermal flow behaviour around the campus by using Computational Fluid Dynamics (CFD) as a numerical tool. The three dimensional Reynolds-Averaged Navier–Stokes (RANS) equations were solved under FLUENT commercial code to simulate temperature and wind flow parameters at each discretised locations. Field measurements were carried out to validate the results produced by CFD for closer approximation in the representation of the actual phenomenon. Results established that the air temperature is inversely proportional to wind velocity. Hotspots were formed in the zone 1 and 3 region with a temperature rise of 9.1% that caused a temperature increase of 2.7 °C. Observations illustrated that the building configuration altered the wind flow pattern where the wind velocity was higher in the zone 2 region. Findings determined increase in the sensible cooling load by 19.61% due to 1.22 °C temperature rise. This paper highlighted the application of CFD in modelling an urban micro-climate and also shed light into future research development to quantify the HIs.
Highlights
Over the last few years, the world has been rapidly developing towards urbanisation that is negatively affecting the environment leading to a substantial increase in the cooling requirements
The findings indicated those specific locations in the zone 1 and 3 region experienced 9.1% increase in the ambient temperature which caused a temperature increase of 2.7 °C leading to the formation of hotspots in these regions
The findings determined that wind flow pattern and speed was one of the major factors in the formation of higher temperatures along with the building geometry that altered the wind velocity and high convective heat exchanges from glazing façade with relatively high surface temperature
Summary
Over the last few years, the world has been rapidly developing towards urbanisation that is negatively affecting the environment leading to a substantial increase in the cooling requirements. The increase in the surface temperature of urban structures leads to alteration of urban microclimate as a result of variations in convective heat exchanges from these surfaces [1]. This leads to an increase in the air temperature, where metropolitan cities with hard built-up structures have higher mean air temperatures than the immediate rural areas surrounding it. Oke [2] portrayed the heat island phenomenon as the heat being trapped within the densely built up urban areas leading to elevated ambient air temperatures in the centre of the city as compared to the surrounding outlying areas. Tam et al [3] mentioned it as an anthropogenic phenomenon due to modifications of the urban surfaces by human
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