Applications of an Embedded Seamless Hybrid RANS/LES Approach for Turbulent Dispersion over Complex Urban Areas

This work presents an application of a RANS/LES hybrid approach in simulating flows and turbulent dispersion in complex urban areas. It is demonstrated that the
hybrid approach correctly captures the time-dependent behavior of the wake regions behind buildings, resulting in improvements of the total turbulent kinetic energy and, consequently, the turbulent dispersion of pollutants.
The seamless variant of the hybrid RANS/LES approach proposed here, based on a dynamic evolution of the local interface zone, in combination with a generic-reaction set atmospheric chemistry model, proved to be numerically efficient and robust, and is recommended for future investigations of turbulent dispersion in real-scale city domains.