Computational fluid dynamics (CFD) has become an essential tool for investigating the effects of the atmospheric boundary layer (ABL) on a wide range of practical applications. However, accurately simulating ABL flows remains challenging, particularly in properly describing boundary conditions and effectively preventing inflow deterioration. While previous studies have primarily focused on neutral ABL conditions, the influence of thermal stratification, driven by daily cycles of surface heating and cooling, is still inadequately addressed. Existing approaches, such as those based on Monin-Obukhov Similarity Theory and the standard gradient diffusion hypothesis, exhibit limitations in capturing turbulent kinetic energy profiles and defining thermal boundary conditions. To overcome these challenges, we propose a unified model for simulating ABL flows across diverse thermal stability regimes. The model integrates local equilibrium theory with the standard gradient diffusion hypothesis within the framework of standard k - ε turbulence model. A set of analytical solutions for inflow profiles and thermal boundary conditions is derived to ensure consistency with the governing transport and energy equations. The model’s performance is validated against wind tunnel experimental data for both wind flow over flat terrain and around a typical building. Results demonstrate that the proposed model maintains horizontal homogeneity and accurately reproduces velocity, turbulence, and temperature profiles under different thermal stratifications, showing good agreement with experimental measurements. Comparative studies further highlight the advantages of the unified model over existing approaches, underscoring its potential for reliable CFD simulation of ABL flows in engineering applications.
Li et al. (Mon,) studied this question.