Large-Eddy Simulation of Turbulent Flow Response to Abrupt Changes in Roughness and Thermal Conditions*

Abrupt transitions in surface roughness and thermal conditions are ubiquitous in both environmental science and engineering applications. However, little is known about the combined effects of these abrupt changes. This study employs Large-Eddy Simulation (LES) techniques to simulate turbulent flows over heterogeneous surfaces with both abrupt changes in surface roughness and thermal conditions. Initially, the development of the internal boundary layer and the variation in momentum flux are observed separately for surface roughness heterogeneity and thermal heterogeneity. Subsequently, the flow behaviors are analyzed when both heterogeneities are present simultaneously. Additionally, this analysis scrutinizes the suitability of the Monin-Obukhov similarity theory, which is developed under homogeneous assumptions, within these contexts. Insights derived from this investigation can facilitate more accurate modeling of turbulence with abrupt changes, improving predictions for both environmental and engineering applications.