Lattice Boltzmann method-based large eddy simulation of turbulent flow over different canopy arrays

Understanding turbulent flows over street canopy is important for predicting the environmental flow dynamics and designing smart cities, but the modeling of such flows is still challenging as more structures of different scales are involved. Three-dimensional time-dependent flow statistics are required for in-depth understanding of these complex flows. Large eddy simulation (LES) is an efficient method for simulating large-scale flow structures but its accuracy remains to be examined. The lattice Boltzmann method-based large eddy simulation (LBM-LES) has gained increasing attention in the engineering fields over the past decades. In this work, the multi-relaxation time (MRT) LBM-LES incorporating Wall-Adapting Local Eddy-Viscosity (WALE) is developed to simulate flow over canopies. Firstly, the code is validated using the flow over a single building with aspect ratio 1:1:2, and a good agreement is found between LBM-LES and the results from the literature. Then, turbulent flows over canopies with different heights and distributions are simulated and results are compared with experimental data. The simulated flows then allow us to explore the differences between mixing-layer analogy and roughness sublayer for this flow configuration.