Coupled urban physics in microclimate modeling: Validating and enhancing simulation tools

• Validated urbanMicroclimateFoam against real-world temperature and humidity data. • Integrated humidity, radiation, and vegetation into CFD urban microclimate modeling. • Achieved RMSE of 1.03 °C and 4.78 % RH, confirming model accuracy for urban settings. • Vegetation modeling showed measurable cooling and humidity increase effects. • urbanMicroclimateFoam balanced model complexity with computational efficiency. Significant advances in microclimate modeling tools range from no coupling to fully coupled urban physics, requiring a tradeoff between simulation speed and accuracy. This study was conducted to validate the urbanMicroclimateFoam solver for accuracy, as a key step toward improving its reliability for urban microclimate modeling. A detailed 3D model was created, and transient simulations were performed and compared against weather station data from Georgia Tech’s campus. The solver includes heat, air, moisture (HAM), radiation (RAD), and vegetation (VEG) physics, and its performance was evaluated in terms of temperature, humidity, and thermal comfort. Results show strong agreement with measured data, achieving a temperature RMSE as low as 1.03 °C and a humidity RMSE of 4.78 % at the best performing location. Simulations also captured diurnal WBGT trends and vegetation driven cooling up to 2.1 °C. The findings highlight the value of fully coupled CFD models for understanding the urban heat island effect and designing more sustainable, climate resilient cities.