An Integrated Multiscale and Multiphysics Urban Microclimate Model for the Urban Thermal Environment

In recent years, cross-scale modelling approaches that integrate or use a combination of one or more of the modelling approaches are being implemented to enhance the accuracy of the urban system modelling. However, the existing atmosphere–urban coupling methods are mainly focused either on the integration of WRF and UCMs or CFD to enhance the accuracy of mesoscale weather forecasts, or the combination of UCMs or CFD based airflow and energy balanced models to estimate cooling/heating loads and energy use in buildings. It notes that a cross-scale atmospheric modelling system involving the interactions of mesoscale, microclimate and building scale is required for urban microclimate and UHI mitigation measures research. This work develops an integrated multiscale and multiphysics atmospheric modelling system by considering the impacts on urban microclimate of multiple physical processes of regional climate, urban climate, building and pavement material properties and anthropogenic heat. It provides a way of coupling WRF, OpenFOAM based CFD and building energy modelling, contributing in the prediction of the overall effectiveness of urban heat island effect mitigation strategies. It considers local area circulations impacts on urban microclimate, and analyses the interactions between anthropogenic heat released from building HVAC systems and the environment in the street canyons. In addition, taking the Kent Ridge Campus of National University of Singapore as a case study, we set up the virtual model of the campus and illustrate how the virtual model can serve in this coupling modelling. We believe this would be useful for CFD simulations at a large scale with the consideration of real terrain.