在颗粒尺度下研究新月形沙丘-新月形沙丘的排斥作用
Barchan-barchan dune repulsion investigated at the grain scale
AI总结：
该研究通过颗粒尺度数值模拟，揭示了新月形沙丘“追逐”相互作用中排斥效应的微观机制，解释了地外及地球沙丘场的沙丘分布规律。
摘要：
新月形沙丘（barchan）是在地球、火星及其他天体上发现的月牙形风成沙丘。在不同类型的新月形沙丘间相互作用中，有一种被称为“追逐（chasing）”的作用模式：沙丘彼此保持靠近但互不接触。本文通过开展颗粒尺度数值计算，探究这种新月形沙丘间排斥作用的起源；计算中，一对颗粒堆在流体流动作用下发生形变，成为相互作用的新月形沙丘。在我们的模拟中，每个独立颗粒的位置、速度、合力等数据都会在每个时间步被计算，使我们能够测量解释排斥作用的流体与颗粒细节。我们展示了颗粒轨迹、时间平均合力以及每个沙丘的质量平衡，并发现下游沙丘的收缩速度快于上游沙丘，因此尽管处于上游沙丘的尾流中，下游沙丘仍能保持相对较高的速度。而这种快速收缩是由流动扰动导致的：流动扰动会使下游沙丘遭受更强的侵蚀，同时上游沙丘脱落的颗粒会绕开下游沙丘。我们的研究结果有助于解释地球和火星上沙丘场中新月形沙丘分布背后的机制。
英文摘要：
Barchans are eolian dunes of crescent shape found on Earth, Mars and other celestial bodies. Among the different types of barchan-barchan interaction, there is one, known as chasing, in which the dunes remain close but without touching each other. In this paper, we investigate the origins of this barchan-barchan dune repulsion by carrying out grain-scale numerical computations in which a pair of granular heaps is deformed by the fluid flow into barchan dunes that interact with each other. In our simulations, data such as position, velocity and resultant force are computed for each individual particle at each time step, allowing us to measure details of both the fluid and grains that explain the repulsion. We show the trajectories of grains, time-average resultant forces, and mass balances for each dune, and that the downstream barchan shrinks faster than the upstream one, keeping, thus, a relatively high velocity although in the wake of the upstream barchan. In its turn, this fast shrinkage is caused by the flow disturbance, which induces higher erosion on the downstream barchan and its circumvention by grains leaving the upstream dune. Our results help explaining the mechanisms behind the distribution of barchans in dune fields found on Earth and Mars.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
