Reynolds-averaged Eulerian simulation of elevated source pollutant dispersion in turbulent boundary layer using concentration diffusivity limiter

Abstract

In this study, a limiter for turbulent concentration diffusivity, accounting for travel time, was introduced into the Reynolds-averaged Navier-Stokes equations (RANS) and the Eulerian dispersion model. Using conventional modeling of turbulent diffusivity with the simplified gradient diffusion hypothesis and a proposed method with a limiter, pollutant dispersion from an elevated point source in a turbulent boundary layer was predicted and the results validated by using data from an existing wind tunnel experiment. By using conventional modeling, it was difficult to give a good prediction of the entire concentration field by only adjusting the turbulent Schmidt number. In contrast, the proposed method controlled the turbulent diffusivity near the source, and in the downwind region, by adjusting the combination of model parameters in the limiter. As a result, the dispersion characteristics (concentration profile and plume half-width) near the source and in the downwind region were simultaneously well predicted. Finally, a parametric study was conducted on the mean concentration, and the optimal combination of model parameters in the limiter showed improved results of validation metrics ( FB=0.04, MG=1.09,NMSE=0.03,VG=1.14) than the conventional modeling ( FB=−0.11, MG=0.75,NMSE=0.11,VG=1.62).