Wind tunnel experiments and multiscale modeling for effects of traffic exhausts on the indoor air quality within urban-scale regions

The multiscale problems in heat/mass transfer and fluid flow can be divided into two categories: multiscale system and multiscale process. The physical phenomena of flow and dispersion of gaseous pollutants in urban-scale regions belong to the multiscale system problems. Our work concentrates on utilizing the multiscale approach to study the impacts of traffic exhausts on the indoor air quality in urban-scale regions which is of multiscal-system type. The computational domain is simplified and divided into three regions with different scale: community level, street level and indoor level, which are solved from top to down and the computational results from the upper level are extracted at the interfaces to be applied as the boundary conditions on the next level analysis. The commercial software FLUENT 14.0 was used for solving the N-S equations in conjunction with RNG κ-ε turbulent model. The wind-tunnel experiments and full-field simulations were both conducted to examine the top-to-down numerical method. It was found that this method was practical and need to be improved for investigating the multiscale problems in urban areas.