Modelling diabatic atmospheric boundary layer using a RANS CFD code with a K-Epsilon turbulence closure

Abstract

In this paper, we present a specific methodology developed to simulate a diabatic (stable or unstable situations) atmospheric Surface Layer (SL) with a CFD approach using the RANS equations closed by a κ-ε turbulence model. This study has been carried out with the CFD software Fluent, but the results presented are of more general interest. In a first part, we propose a set of vertical profiles for velocity, potential temperature, pressure, turbulent kinetic energy and turbulent dissipation rate in a diabatic SBL and we discuss the consistency of these profiles with the equations solved in a RANS CFD code with a κ-ε turbulence model. We show that a parameterization for σ κ and σ ε can improve this consistency. In the second part, we describe a set of boundary conditions used to simulate a steady homogeneous SL. In the last part, we discuss some results which illustrate the ability of the present approach to reproduce and maintain the different profiles predicted by the Monin-Obukhov similarity theory.