Collapse-driven formation of a tetratic structure of confined quasi-2D granular tubes

Abstract

A tetratic phase, characterized by four-fold orientational symmetry, is observed in an experimental quasi-2D system of tubular particles subject to granular collapse. Evidence is presented that the cell's aspect ratio primarily affects the fraction of particles aligned along the length of the cell and not the overall degree of tetratic order as measured by the tetratic order parameter $S_{4}$, and that granular collapse enhances tetratic order beyond the effect of increasing the effective local density.