Reciprocal swimming in viscoelastic granular hydrogels

Fuente: arXiv
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Autores principales: Xiao, Hongyi, Wang, Jing, Sack, Achim, Stannarius, Ralf, Pöschel, Thorsten
Formato: Preprint
Publicado: 2025
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author Xiao, Hongyi
Wang, Jing
Sack, Achim
Stannarius, Ralf
Pöschel, Thorsten
author_facet Xiao, Hongyi
Wang, Jing
Sack, Achim
Stannarius, Ralf
Pöschel, Thorsten
contents We experimentally study a scallop-like swimmer with reciprocally flapping wings in a nearly frictionless, cohesive granular medium consisting of hydrogel spheres. Significant locomotion is found when the swimmer's flapping frequency matches the inverse relaxation time of the material. Remarkably, the swimmer moves in the opposite direction compared to its motion in a cohesion-free granular material of hard plastic spheres. At higher or lower frequencies, we observe no motion of the swimmer, apart from a short initial transient phase. X-ray radiograms reveal that the wing motions create low-density zones, which in turn give rise to a hysteresis in drag and propulsion forces. This time-dependent effect, combined with the swimmer's inertia, accounts for locomotion at intermediate frequencies.
format Preprint
id arxiv_https___arxiv_org_abs_2510_16586
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Reciprocal swimming in viscoelastic granular hydrogels
Xiao, Hongyi
Wang, Jing
Sack, Achim
Stannarius, Ralf
Pöschel, Thorsten
Soft Condensed Matter
Fluid Dynamics
We experimentally study a scallop-like swimmer with reciprocally flapping wings in a nearly frictionless, cohesive granular medium consisting of hydrogel spheres. Significant locomotion is found when the swimmer's flapping frequency matches the inverse relaxation time of the material. Remarkably, the swimmer moves in the opposite direction compared to its motion in a cohesion-free granular material of hard plastic spheres. At higher or lower frequencies, we observe no motion of the swimmer, apart from a short initial transient phase. X-ray radiograms reveal that the wing motions create low-density zones, which in turn give rise to a hysteresis in drag and propulsion forces. This time-dependent effect, combined with the swimmer's inertia, accounts for locomotion at intermediate frequencies.
title Reciprocal swimming in viscoelastic granular hydrogels
topic Soft Condensed Matter
Fluid Dynamics
url https://arxiv.org/abs/2510.16586