Urban Wind and Thermal Environment Simulation - A Case Study of Gävle, Sweden

Abstract: As urbanization and industrialization progressed during the last decades, Urban Heat Island (UHI) has become a major environmental issue to many cities around the world. The effect of UHI differs from area to area due to varying urban scale, population density, construction of urban surface layer, the level of industrialization and type of climate. Researchers have made great efforts in investigating various approaches to Urban Heat Island studies. Monitoring technologies have been widely used in this field, especially Geographic Information System (GIS) and remote sensing technology. Computational Fluid Dynamics (CFD) simulations are also actively applied in wind engineering, which can provide details of air flow over urban areas. The combined application of these technologies can provide the monitoring and simulation of urban wind corridor and thermal environment that can produce relevant information at a lesser time.A research using GIS, remote sensing technology and CFD simulation was done in this project to obtain a holistic view of the urban thermal environment and wind flow for Gävle City. With GIS and remote sensing the thermal image of the city was presented. The temperature data, which were collected from MODIS satellite were transferred and processed by ArcGIS and Global Mapper. The wind flow above the city was simulated through constructing geometric and mathematical model with OpenFOAM. The outcomes of the modeling and simulation identified that the temperature in the city center could possibly reach 35℃ during summers, which can cause the Urban Heat Island to form. Ventilation was also poorer in the city centre, and neither the river nor the green area in the southwest could help ventilate the city. The study result also suggested that certain sites in the city had relatively high wind flow for urban wind turbines to work.This study had used method of Urban Heat Island study with remote sensing and CFD technologies. The model produced from simulation could also be used to further study Gävle city's thermal and wind environment to produce more accurate results.