Numerical estimation of the external convective heat transfer coefficient for buildings in an urban -like setting

Current external convective heat transfer coefficient estimation methods are known to introduce significant uncertainty in energy consumption evaluations for building with complex surrounding conditions. In this study, the impact of built area density (aggregation or rarefaction) on convective heat transfer from buildings is numerically investigated in an urban-like setting. Arrays of cubical buildings with twelve different packing density in different flow regimes including three isolated, five wake interference and four skimming flow regimes, and an isolated cube case for comparison have been investigated. Reynolds stress turbulence model (RSM) is used for closure of the steady Reynolds averaged momentum and energy equations. The results indicate that the behavior of convective heat transfer varies from one flow regime to another. The convective heat transfer coefficient (CHTC) trends in the isolated flow regimes are characterized by sharp changes with density; whereas in the interference and skimming flow regimes the CHTC gently decreases with the increase of built area density. New correlations for estimating CHTC in these three regimes are proposed. The proposed correlations are expected to enable estimation of CHTC for buildings located in urban neighborhoods based on the built area density.