Modification to aerosols dispersion algorithms over two-dimensional hilly terrain based on wind tunnel atmospheric experiments

Abstract

Accurate prediction of aerosol atmospheric dispersion concentration distribution in airborne effluents from nuclear power plants is very important for environmental assessment and nuclear accident emergency response. This study focuses on the plume dispersion centerline trajectory and concentration distribution of aerosols in the atmospheric boundary layer over a two-dimensional hill model under neutral atmospheric conditions. Through laser measurements in active atmospheric dispersion wind tunnel experiments, the flow field around the hill and the aerosol dispersion concentration distribution released at different heights were obtained. According to the streamlines and considering the lifting effect of hill on plumes, a modification algorithm for plume centerline trajectories and concentration distribution in hilly terrain based on Gaussian dispersion model was proposed. The plume centerline trajectory and concentration distribution simulated by the modification algorithm and Plume Path Coefficient Treatment are compared with the experimental results. The results showed that due to the influence of clockwise circulation on the leeside of the hill, the aerosol dispersion trajectory was separated from the shape of the hill. The modification algorithm has better agreement with the experimental results, with NMSE and FB in $0\text{–}0.025$, in the simulation of the plume centerline trajectory. For the simulation of concentration distributions, the modification algorithm slightly underestimates, but is more stable than Plume Path Coefficient Treatment, which has the performance that goes from far overestimation to underestimation along the downwind direction. This study can provide an accurate evaluation of aerosols atmospheric dispersion over hilly terrain.