Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Aug;80(2):020301. doi: 10.1103/PhysRevE.80.020301. Epub 2009 Aug 07.

Swimming in granular media.

Physical review. E, Statistical, nonlinear, and soft matter physics

Takashi Shimada, Dirk Kadau, Troy Shinbrot, Hans J Herrmann

PMID: 19792063 DOI: 10.1103/PhysRevE.80.020301

Abstract

A class of reptiles known as sand swimmers adapts to hot environments by submerging beneath desert sands during the day and so provide a unique probe into the dynamics of intruders in granular beds. To understand the mechanism for swimming in an otherwise solid bed, we study a simple model of periodic contraction and extension of large intruders in a granular bed. Using an event-driven simulation, we find optimal conditions that idealized swimmers must use to critically fluidize a sand bed so that it is rigid enough to support a load when needed, but fluid enough to permit motion with minimal resistance. Swimmers-or other intruders-that agitate the bed too rapidly produce large voids that prevent traction from being achieved, while swimmers that move too slowly cannot travel before the bed resolidifies around them, i.e., the swimmers locally probe the fundamental time scale in a granular packing.

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't