Buckling, Crumpling, and Tumbling of Semiflexible Sheets in Simple Shear Flow

TL;DR

This study uses numerical simulations to explore how semiflexible 2D sheets behave in shear flow, revealing buckling, crumpling, and tumbling phenomena influenced by their stiffness and initial orientation.

Contribution

It provides new insights into the complex fluid-structure interactions of semiflexible sheets, including buckling modes and tumbling dynamics, which were previously not well understood.

Findings

Buckling instabilities depend on bending stiffness.

Sheets fold or crumple before tumbling.

Sheets do not stretch again after crumpling.

Abstract

As 2D materials such as graphene, transition metal dichalcogenides, and 2D polymers become more prevalent, solution processing and colloidal-state properties are being exploited to create advanced and functional materials. However, our understanding of the fundamental behavior of 2D sheets and membranes in fluid flow is still lacking. In this work, we perform numerical simulations of athermal semiflexible sheets with hydrodynamic interactions in shear flow. For sheets initially oriented in the flow-gradient plane, we find buckling instabilities of different mode numbers that vary with bending stiffness and can be understood with a quasi-static model of elasticity. For different initial orientations, chaotic tumbling trajectories are observed. Notably, we find that sheets fold or crumple before tumbling but do not stretch again upon applying greater shear.