论文标题
串联杆在颗粒状沉积物中的串联杆的非添加阻力
Nonadditive drag of tandem rods drafting in granular sediments
论文作者
论文摘要
我们研究了一对垂直杆在串联的颗粒床中移动的一对垂直杆所经历的阻力，这是浸入液体中的分离距离和速度的函数。与牛顿流体一样，杆的净阻力最初会随着平稳的距离的距离而增加，直到高平原到值的两倍。但是，与孤立杆相比，在两根杆上的阻力作用大不相同，而领先的杆经历了大致相似的阻力，而以下杆经历的阻力要少得多。在干燥的颗粒床中观察到阻力与领先物体和随后的身体之间的异常关系，同时浸入了准静态的粘液牛顿液体和依赖速率依赖性方案中。通过折射率匹配，我们可以看到超过两个杆的沉积物流，并表明停滞的区域在杆之间的参考框架中形成，以进行小分离。因此，随着分离距离的降低，以下杆越来越避免避免颗粒流，从而导致净阻力较低。应根据我们的结果将电阻理论应用于在颗粒沉积物中移动的多组分对象时应注意，因为我们的结果是在短距离距离时阻力不是加性的。
We examine the drag experienced by a pair of vertical rods moving in tandem through a granular bed immersed in a fluid as a function of their separation distance and speed. As in Newtonian fluids, the net drag experienced by the rods initially increases with distance from the value for a single rod before plateauing to twice the value. However, the drag acting on the two rods is remarkably different, with the leading rod experiencing roughly similar drag compared to a solitary rod, while the following rod experiences far less drag. The anomalous relationship of drag and the distance between the leading and following body is observed in both dry granular beds and while immersed in viscous Newtonian fluids across the quasi-static and the rate-dependent regimes. Through refractive index matching, we visualize the sediment flow past the two rods and show that a stagnant region develops in their reference frame between the rods for small separations. Thus, the following rod is increasingly shielded from the granular flow with decreasing separation distance, leading to a lower net drag. Care should be exercised in applying resistive force theory to multi-component objects moving in granular sediments based on our result that drag is not additive at short separation distances.
