CFD modelling of an urban microclimate during a heat wave: Coupling solar radiation and heat transfer
Dryelle Mendes Souza Nascimento, Ana Ascenso, Diogo Lopes, Myriam Lopes, Vera Rodrigues
Abstract
In urban areas, the complex nature of the built environment is critical in shaping the local microclimate, strongly influencing heat transfer mechanisms and solar radiation dynamics. In this study, a dedicated module was developed within the open-source Computational Fluid Dynamics model OpenFOAM to evaluate the local urban microclimate. A set of simulations were performed for the University of Aveiro campus (Portugal), during a heat wave. This work aims to compare two distinct approaches for simulating wall thermal behaviour: one assumes surfaces and walls as adiabatic, while the other incorporates convective and radiative processes at surfaces and building walls. The latter approach enables a more accurate representation of spatial temperature variations in urban areas, particularly when also considering solar radiation input. The overall results emphasize the role of accounting for heat transfer mechanisms and solar radiation dynamics. Large differences were found in the modelled near-wall air temperatures, mainly at the leeward side of buildings and during the hours of higher solar radiation. This paper’s novelty stems from the development of the OpenFOAM CFD model, coupling surface heat transfer mechanisms with solar radiation dynamics. We demonstrate its capabilities through testing and evaluating its performance in assessing the local microclimate.