Erosion and Deposition Patterns Over a Wind-Blown Sand Dune Behind a High Vertical-Type Sand Fence

Sand dunes are the primary factor influencing wind-sand disasters. To explore the evolution law of wind-blown sand dunes surrounding high vertical-type sand fences along desert railways, numerical simulation analyses based on computational fluid dynamics coupled with a discreet element method of the wind-sand flow field and sand particles trajectories around sand fences were conducted. The focus of this study was the Yandun section of the Lanzhou-Xinjiang Railway in Xinjiang, China (42.38 degrees N, 93.95 degrees E). By combining ERA5 wind data with field measurements and monitoring, a three-dimensional coupling model was established. According to the results of L9 (33) orthogonal tests, the sensitivity of the three factors to the evolution of sand dunes can be ordered as wind speed > porosity > height, indicating that wind speed is closely related to sand dune evolution (p < 0.05). The results of single-factor tests indicate that the structure of wind-sand flow fields, sand accumulation patterns, and sand particle movement trajectories vary significantly under different wind speeds. The sand accumulation rates on the windward slope of the sand dune are 29.67%, 25.91%, and 20.04%, while on the leeward slope, these rates are 40.33%, 34.09%, and 29.96%, respectively. The obtained information on the evolution law of sand dunes surrounding high vertical-type sand fences provides a scientific basis for wind-sand prevention measures along railways in desert regions.