Sensitivity analysis of the OpenFOAM LES simulations performed on the 3D urban array structure

This study presents the outcome of a series of different street scale Large Eddy Simulations (LES) performed on a 3D urban array. The configuration and the setup of these simulations are built upon the results previously published by Nosek et al., 2018, BAE 138; Kluková et al., 2021, JWEIA 208. The LES simulations are focused on the turbulent flow, passive scalar transport, and dispersion within and above the previously mentioned 3D urban array which portrays a typical building setup present in many cities across Europe. This study is connected to the project named “The Role of coherent structures’ dynamics on scalar transport and dispersion in the urban canopy layer” and it is backed up by the experimental data obtained in the wind tunnel measurements.

The LES computations are carried out by the open-source computational fluid dynamics (CFD) software called OpenFOAM.  The simulations differ in terms of resolution and refinement of the computational grid within the street canyons of the urban array, the type of solvers used (e.g., pimpleFoam or a solver based on a projection method), and the boundary conditions imposed (periodic and turbulent inlet boundary conditions). The comparison between the LES and Detached Eddy Simulation (DES) approach is investigated and presented as well.

The findings of this study are serving to a better understanding of how well the different setups and configurations of the OpenFOAM LES simulations are capable of representing the turbulent structures in the street canyons and their influence on the passive scalar dispersion. In addition, the results confirm the optimal OpenFOAM simulation setup for the investigation of these types of problems.