An extended SST k-? framework for the RANS simulation of the neutral Atmospheric Boundary Layer

The use of Computational Fluid Dynamics (CFD) for environmental studies is continuously growing. In this context, simulations are usually carried out solving Reynolds-averaged Navier-Stokes (RANS) equations that require an appropriate implementation of the Atmospheric Boundary Layer (ABL).This paper proposes a framework based on the Shear Stress Transport (SST) k-! turbulence model, which is highly recommended for microclimate analysis, since it is known to well reproduce homogeneous ABL flows in the context of RANS simulations. Besides, a new blending approach is developed to account for the presence of obstacles in the domain. The model is implemented in the open-source OpenFOAM code and validated against well-known benchmark cases spanning different configurations, i.e., an empty fetch, a single building and an array of buildings.The performance of the proposed model is very satisfactory. For instance, the Factor-of-2 validation metric is FAC2>0.8 for both velocity and turbulent kinetic energy in nearly all cases.