ABSTRACT Knowledge of wind flow over dune scarps and, as scarps fill, their subsequent various slopes, is important for understanding sediment transport pathways from beach to dunes. In this study, flow over scarps (also termed forward-facing steps) is reviewed, and the flow over a vertical scarp (90°) and three slopes of 45°, 24°, and 14°, all 2 m in height, is examined via CFD modelling. The flow over three 90° scarps, with heights of 1 m, 2 m and 4 m, and over a 2-m high vertical (90°) scarp for three oblique incident winds is studied. The extent of wind flow deceleration and separation becomes smaller with decreased slope, with maximum flow separation and reverse vortex development occurring on the vertical scarp. The extent of crest wind flow separation is greatest for the scarp and considerably less for the 45° slope. As scarp height increases, so too does the spatial extent of turbulent wind flow, wind speed, and extent of the flow separation region. As incident wind direction became more oblique over a vertical scarp, less deceleration occurs, and helicoidal vortices replace roller vortices. Our results demonstrate how scarp morphology and wind direction are likely to influence transport pathways. Graphical Abstract

中文翻译：

---

模型陡坡和斜坡上的 CFD 流动动力学

摘要 沙丘陡坡上的风流以及陡坡填满后的各种坡度的知识对于理解从海滩到沙丘的沉积物输送路径很重要。在本研究中，回顾了陡坡（也称为前向台阶）上的水流，垂直陡坡 (90°) 和 45°、24° 和 14° 三个斜坡上的水流均为 2 m，为通过 CFD 建模检查。研究了三个倾斜入射风在三个 90° 陡坡上的流动，高度分别为 1 m、2 m 和 4 m，以及在 2 米高的垂直 (90°) 陡坡上的流动。风流减速和分离的程度随着坡度的减小而变小，垂直陡坡上出现最大的流分离和逆涡发展。陡坡峰顶风流分离的程度最大，而 45°坡度的峰顶风流分离程度要小得多。随着陡坡高度的增加，湍流风流的空间范围、风速和流动分离区域的范围也会增加。随着入射风向在垂直陡坡上变得更加倾斜，减速发生的程度降低，螺旋涡流取代了滚柱涡流。我们的结果证明了陡坡形态和风向可能如何影响运输路径。图形概要