Quantifying the uncertainty of the effects of varying wind conditions on outdoor airflow and pollutant dispersion

Studying gaseous pollutant dispersion in outdoor settings is essential to preventing pollution of the environment around buildings and protecting public health. Wind conditions are constantly changing, resulting in variability and uncertainty in airflow and pollutant dispersion. Past studies have investigated the impact of wind conditions primarily through the sampling method, which is inefficient. This study quantified the uncertainty in the effects of varying wind conditions on air velocity and pollutant concentration using the polynomial chaos expansion method, which approximates velocity and concentration results by expanding orthogonal polynomials with wind direction and wind speed as input variables. The obtained the polynomials of velocity and pollutant concentration with wind condition can achieve 0.91–0.98 accuracy. This method allows for quick calculations of velocity and concentration results, providing the distributions of velocity and concentration with respect to wind conditions. It enables direct and rapid prediction of air velocity and pollutant concentration, avoiding the need for repeated simulations due to varying wind conditions and thus improving computational efficiency. This approach provides more comprehensive information about pollution dispersion in actual urban environments.