Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 54: Active Matter II (joint session DY/BP/CPP, organized by DY)

CPP 54.7: Talk

Thursday, March 23, 2017, 11:30–11:45, HÜL 186

Mechanical Instabilities in Active Systems — •Christoph A. Weber and Lakshminarayanan Mahadevan — Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA

Active stress can affect the stability of biological systems and drive macroscopic changes of matter on very short time scales that cannot be explained by the liquid-like transport of the constituents. Examples are contracting active gels or the compaction of cells in tissues. For these systems the solid-like response to active stress is the key to understand the physics underlying the change of matter. Here we study a generic framework to describe mixtures composed of an active solid and a passive liquid phase. We find that such a mixture is unstable for large enough activity and can demix into regions mostly consisting of solid or fluid, respectively. The instability leads to the formation of disintegrated patches of a length scales which arises from the competition between the shear transport in the solid phase versus the solid-liquid momentum transfer. This mechanical instability might be relevant for many very dense active systems where liquid-like particle transport is mostly jammed.