Large-Eddy Simulation of the Atmospheric Boundary Layer with Near-Wall Resolved Turbulence

In this study, a large-eddy simulation (LES) code with the one-dimensional turbulence (ODT) wall model is tested for the simulation of the atmospheric boundary layer under neutral, stable, unstable and free-convection conditions. The ODT model provides a vertically refined flow field near the wall, which has small-scale fluctuations from the ODT stochastic turbulence model and an extension of the LES large-scale coherent structures. From this additional field, the lower boundary conditions needed by LES can be extracted. Results are compared to the LES using the classical algebraic wall model based on the Monin–Obukhov similarity theory (MOST), showing similar results in most of the domain with improvements in horizontal velocity and temperature spectra in the near-wall region for simulations of the neutral/stable/unstable cases. For the free-convection test, spectra from the ODT part of the flow were directly compared to spectra generated by LES-MOST at the same height, showing similar behaviour despite some degradation. Furthermore, the additional flow field improved the near-wall vertical velocity skewness for the unstable/free-convection cases. The tool is demonstrated to provide adequate results without the need of any case-specific parameter tuning. Future studies involving complex physicochemical processes at the surface (such as the presence of vertically distributed sources and sinks of matter and energy) within a large domain are likely to benefit from this tool.