چكيده به لاتين
In the present dissertation, the effects of cross-ventilation on flow field and passive pollutant dispersion have been analyzed, using the large eddy simulation (LES) approach. Due to the development of cities and industries, scientists have focused on passive pollutant dispersion in urban areas. Also, the issue of pollutant dispersion inside the buildings has become of great concern since, nowadays, people are spending most of their times indoor. At first, the present dissertation, passive pollutant dispersion, natural ventilation, and their different aspects have been addressed. In the next chapter, a detailed review of the literature has been presented. Moreover, the methods used for the simulations have been explained. Furthermore, three different sub-grid scale (SGS) models, namely, standard Smagorinsky-Lilly, dynamic Smagorinsky-Lilly, and WALE, employed for the simulations have been explained. Boundary conditions and computational domains of the present simulations have also been discussed. Next, the results of the simulations have been presented. The results of the flow and the passive pollutant fields have been compared with the available wind-tunnel data. The WALE sub-grid scale model has been selected as the most suitable SGS model among the above-mentioned ones since it predicts the passive concentration field more accurately with less required CPU time. Furthermore, the effects of the shape of openings on flow field and passive pollutant dispersion have been investigated using three different building configurations, namely, horizontal opening, square opening, and vertical opening. The results show that the third case, building with vertical openings, is the least contaminated one. Therefore, the performance of cross-ventilation in this case is the most effective one. Moreover, the contribution of the convective flux and turbulent diffusion flux to the passive pollutant transportation has been studied. Present findings show that the participation of the turbulent diffusion flux in the passive pollutant transportation becomes lower as the flow makes progress toward the downstream.
Keywords: Cross-ventilation, pollutant dispersion, large eddy simulation (LES), sub-grid scale model
