Surface roughness, energy distribution, and scale of structures for the atmospheric boundary layer.

This article focuses on the use of wall-modeled large-eddy simulation (WMLES) to investigate how different types of surface roughness—homogeneous, abrupt, and alternating—affect the energy distribution and structural characteristics of the atmospheric boundary layer. The study finds that increasing surface roughness enhances the energy of small-scale motions (SSMs) while reducing that of large-scale motions (LSMs) and very-large-scale motions (VLSMs), with abrupt roughness transitions producing double energy peaks near the wall and alternating roughness intervals influencing the energy and scale of VLSMs. The scale of streamwise turbulent structures depends on surface roughness, height above the wall, and the interval of roughness alternation, while the structure inclination angle increases with roughness. These findings have implications for understanding surface–atmosphere interactions and material transport, particularly in contexts such as wind energy and erosion prevention.