Large-scale structures of wall-bounded turbulence in single- and two-phase flows: advancing understanding of the atmospheric surface layer during sandstorms

Graphical Abstract In recent years, observations of the atmospheric surface layer have greatly promoted research on high-Reynolds-number wall-bounded turbulence, especially observations of wind-blown sand flows/sandstorms, which are typical sand-laden two-phase flows; these successes have advanced the science of gas–solid two-phase wall-bounded turbulence to very-high-Reynolds-number conditions. Based on a review of existing atmospheric surface layer observations and the development process, this paper summarizes the important promoting effect played by these observations in understanding the very-large-scale structure characteristics, turbulent kinetic energy fraction and amplitude modulation effect, and in reconstructing the spatial electric field under high-Reynolds-number wall turbulence. This review focuses on the main successes achieved by the observation of sand-laden two-phase flows and the three-dimensional turbulent flow field, especially in the streamwise direction. Finally, some suggestions and outlooks for further research on particle-laden two-phase wall-bounded turbulence under high-Reynolds-number conditions are presented.