RANS simulation of ABL flow over complex terrains applying an Enhanced k-ε model and wall function formulation: Implementation and comparison for fluent and OpenFOAM

The simulation of Atmospheric Boundary Layer (ABL) flows is commonly performed using commercial CFD codes with RANS turbulence modeling, applying the standard k-ε model. However, when applied to the simulation of the homogenous ABL, this approach may result in an undesired decay of the velocity and turbulent fully–developed profiles specified at the inlet of the computational domain. This behavior is due to an inconsistency between turbulence model, inflow conditions and wall function formulation. An approach has been introduced recently to overcome this problem, which consists in the modification of the turbulence model and wall function formulation to retrieve an overall consistent treatment of the neutral ABL. Such methodology, previously applied to simulation of the atmospheric boundary layer over flat terrain and ground-mounted bluff bodies, is here applied to the simulation of the flow over complex terrains and hills, at wind tunnel and atmosphere scale. In a time of limited scientific funding, the availability of open source CFD software such as OpenFOAM is a very attractive option to investigate; therefore, a comparison between OpenFOAM and the commercial code FLUENT 13.0 has been carried out in the present paper. The potential of the proposed methodology and the satisfactory performances of OpenFOAM are demonstrated.