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Pushy Random Walk: A Minimal Model for Transport in Deformable Media
Phys. Rev. Lett. 137, 037101 – Published 13 July, 2026
DOI: https://doi.org/10.1103/7hjs-rx8d
Abstract
We introduce the pushy random walk, where a walker can push multiple obstacles, thereby penetrating large distances in environments with finite obstacle density. This process provides a minimal model for experimentally observed interactions of active particles with dense, deformable media. Using scaling arguments and numerical simulations, we show that in one dimension the walker carves out an obstacle-free cavity whose length grows subdiffusively with time. In two dimensions, increasing obstacle density drives a transition from free diffusion to localized behavior, where the walker is trapped within a cavity whose radius again grows subdiffusively with time. These results show how tracer-induced rearrangements qualitatively reshape transport in crowded media.
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- See Supplemental Material at http://link.aps.org/supplemental/10.1103/7hjs-rx8d for videos demonstrating the dynamics of the pushy random walk in 2D.
