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The interaction between sand particles and sand bed is a key part for the study of wind‐blown sand. The splash functions obtained from experimental observations are of great significance to help us understand relevant physical processes. Due to the adoption of substitute material in experiment and immoderate assumptions in numerical simulation, the results of previous studies are still debatable. This paper experimentally studies on splash functions of natural eolian sand particles by using a self‐developed particle emission system to simulate the splash process. Based on the high‐speed photography technique, the distribution of the angle, speed, and number of the liftoff particles and its quantitative characterization are obtained. The mathematical expectations of relevant variables from this work are comparable with existing results but are quantitatively different from the measured data of substitute particles or the numerical simulated results. More importantly, the detailed statistical characteristics of the natural eolian sand splash function are also extracted from our experimental data, which are really significant for elaborative wind‐blown sand study in the future.

Straw checkerboard barrier (SCB) array is one of the most effective and widely used measures for antidesertification projects. The efficiency and durability of SCB are greatly influenced by the features of wind field and sand particle motion. Unfortunately, very few studies have explored the characteristics of turbulent flow and the internal erosional form inside the barrier cell, because of the complexity of turbulent flow and the sand particle motion around the surface of SCBs. In this paper, we simulated the wind-sand flow around SCBs using 3-D hybrid Reynolds-averaged Navier-Stokes/large eddy simulation method and Lagrangian particle tracing method to analyze the characteristics of turbulent flow, particle motion, and internal erosional form of SCBs. The results show that the vast majority of particles fall into SCB cells from their middle and posterior parts when wind-sand flow passes SCBs, due to the impact of gravity and subsidence flow. It indicates that SCBs could effectively prevent sand flow-induced hazards. The turbulent flow in SCBs has great instantaneous pulse velocity, resulting in retransfer of sand particles in SCBs. Analysis of the mean flow field in SCB found one huge streamwise vortex that filled the SCB cells and two spanwise vortexes in the back of SCB cells. These vortexes will drive particles inside SCBs to move toward the front and side walls, making the erosional form of SCB cells low in the middle and high near all the sides.Plain Language Summary Straw checkerboard barrier (SCB) is the most representative anti-desertification measure and plays a significant role in anti-desertification projects. We studied the wind-sand flow around SCBs using computational method and analyzed the characteristics of turbulent flow, particle motion and internal erosional form of SCBs. Based on the simulation results, the weakness of current SCBs can be identified. Therefore, this research is of significance in improving artificial sand control measures designed to help combat desertification control.

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A bridge built inside the reversed flow region of a sand dune will change the characteristics of wind-sand movement in this region. The Reynolds-averaged Navier-Stokes simulation and discrete particle tracing are used to simulate the wind-sand movement around a sand dune with a bridge built inside the reversed region. Three cases with different bridge positions are studied. The results show that 1) compared with the isolated dune case, a tall bridge built at the leeward toe leads to an increase in the deposition rate on the leeward slope and a longer reversed flow region downstream of the sand dune; meanwhile, the high speed of crosswind on the bridge indicates that some measures should be taken to protect trains from strong crosswind; 2) a low bridge at the leeward toe has little effect on the sand deposition and reversed flow region of the dune; however, low sand transport rate and crosswind speed on the bridge show that anti-crosswind/sand measures should be taken according to the actual situation and 3) a low bridge on the leeward slope has little effect on the length of reversed flow region, however, high crosswind speed and sand flux on the bridge reveal the need of anti-crosswind/sand measures on the bridge. Moreover, the bridges in the reversed flow region increase the sand flux near the leeward crest; as a result, the moving patterns of the sand dune are changed.