Physics
Nonadditive drag of tandem rods drafting in granular sediments
Document Type
Article
Abstract
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 quasistatic 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 multicomponent objects moving in granular sediments based on our result that drag is not additive at short separation distances.
Publication Title
Physical Review E
Publication Date
3-2022
Volume
105
Issue
3
ISSN
2470-0045
DOI
10.1103/PhysRevE.105.034901
Keywords
drag, granular flows, locomotion, sediment transport, granular materials
Repository Citation
Chang, Brian and Kudrolli, Arshad, "Nonadditive drag of tandem rods drafting in granular sediments" (2022). Physics. 83.
https://commons.clarku.edu/faculty_physics/83
Cross Post Location
Student Publications
