A Rapid and Reliable Numerical Method for Predictions of Outdoor Thermal Environment in Actual Urban Areas

Abstract

To analyze urban thermal environments more rapidly and accurately, a real urban morphology is simulated. Two models are proposed to support Reynolds Averaged Navier Stokes (RANS) simulations including: (1) a Zero-equation (ZEQ) turbulence model for outdoor airflows, and (2) convective heat transfer coefficients (CHTC) on external building surfaces. This study used commercial Computational Fluid Dynamics (CFD) software to implement the newly derived ZEQ turbulence model and CHTC wall boundary conditions. This modified version of CFD software was used to predict the thermal environment of an actual urban area including air temperatures and wind velocities. The simulated air velocities around the buildings are compared with the velocities obtained with the standard k-ε (SKE) turbulence model. The air temperatures around the buildings were compared with measured data in the actual outdoor environment. The comparisons show that this simulation method can rapidly and reliably predict a real outdoor thermal environment in an urban area.