CFD simulation of the near-neutral atmospheric boundary layer: New temperature inlet profile consistent with wall functions

Abstract

Accurate Computational Fluid Dynamics (CFD) simulations of Atmospheric Boundary Layer (ABL) flow are essential for a wide range of applications, including atmospheric heat and pollutant dispersion. An important requirement is that the imposed inlet boundary conditions should yield vertical profiles that maintain horizontal homogeneity (i.e. no streamwise gradients) in the upstream part of the computational domain for all relevant parameters, including temperature. Many previous studies imposed a uniform temperature profile at the inlet, which has often led to horizontal inhomogeneity of the temperature profile. This study presents a new temperature inlet profile that can yield horizontal homogeneity for neutral and near-neutral ABL conditions when used in combination with the Standard Gradient Diffusion Hypothesis (SGDH) and a temperature wall function. The horizontal homogeneity by this profile is verified by 2D Reynolds-Averaged Navier-Stokes (RANS) CFD simulations performed with the standard k-ε turbulence model and the SGDH. The approach in this paper can be extended to other types of wall functions and other RANS closure schemes for Reynolds stresses and turbulent heat fluxes.