Numerical simulation method for sensible heat flux from building external surfaces to the surrounding atmosphere using a heat balance simulation and CFD

摘要

Sensible heat flux from building external surfaces is one of the essential factors causing urban heat island effects.In order to predict it accurately, this study uses numerical method that applies the 3D CAD-based heat balance simulation which can calculate the detailed surface temperature distribution taking into account building geometry, and couples it with Low Reynolds number k-ε model (Low-Re model) for CFD simulation.By using the Low-Re model, it is possible to simulate air temperature and wind speed distribution inside the wall boundary layers.This study is implemented to figure out the appropriate prediction formula for CHTC (Convective heat transfer coefficient) that can be used for the prediction of heat fluxes by high Reynolds number k-ε model (High-Re model), in order to apply this method to the analysis of urban block scales.I used the High-Re and Low-Re models to predict CHTC and compared them with that of a wind tunnel experiment.It shows that Low-Re model can predict CHTC accurately.Then I coupled the heat balance simulation and CFD using the Low-Re model to predict the sensible heat flux of an apartment.I obtained the experimental approximation formula for CHTC that can be applied to the High-Re model.