Title: Active intruder dynamics in granular sediments

Author (None): Arshad Kudrolli, Clark University

Abstract:

We investigate the dynamics of an active intruder embedded within granular sediments, motivated by problems in biolocomotion and soft robotics. The intruder, modeled as a cylinder with a diameter significantly larger than the grain size, is driven by horizontal oscillatory forcing. We demonstrate that above a threshold forcing amplitude, the intruder can rise through the granular bed across a broad range of physical conditions. In addition, forward locomotion emerges, with its dynamics is strongly influenced by the elasticity of the cylinder. We interpret these behaviors in terms of lift generation and the underlying granular rheology, highlighting the role of force asymmetries induced by oscillatory motion. The observed mechanisms are contrasted with the classical Brazil nut effect, emphasizing the distinct physics governing active versus passive segregation in granular media.