Yielding Transition in Active Systems

Active matter is a growing area of recent interest due to the wide range of fascinating systems and phenomena which can be studied[1]. In particular, high-density active systems have yet to be studied intensely, despite having many questions and no answers. This work is focused on a dense active system to understand this dynamic controlled by avalanches, unifying quasistatic and dynamic regimes.

Previous works found significant differences between passive and active systems in the study of amorphous materials at close-to-yielding transition[2]. Otherwise, those differences disappeared when we studied isolated avalanches through quasistatic models. This discrepancy may arise from the dynamic. In order to solve this, we present a model which brings together both regimes: Controlled Relaxation Time Model (CRTM). It allows the system to relax until a fixed time instead of total relaxation.

Using CRTM, we modeled an active system composed of soft disks. We characterized the dynamic through avalanche size and its correlation length and times to establish a scale relation.

[1] Vicsek, T., Zafeiris, A. (2012). Collective motion. Physics reports, 517(3-4), 71-140.

[2] Villarroel, C., D ̈uring, G. (2021). Critical yielding rheology: from externally deformed glasses to active systems. Soft Matter, 17(43), 9944-9949.