Novel Experimentally Observed Phenomena in Soft Matter

TL;DR

This paper reviews novel experimental phenomena observed in soft matter, including unusual flow behaviors, turbulence, shear banding, and pattern formation, highlighting the complex rheology and dynamic responses of these mesoscopic materials.

Contribution

It provides a comprehensive review of experimentally observed phenomena in soft matter, emphasizing new flow behaviors and pattern formations not previously documented.

Findings

Observation of turbulent drag reduction in soft materials

Identification of elastic turbulence and shear band formation

Demonstration of flow-induced birefringence and rheological chaos

Abstract

Soft materials such as colloidal suspensions, polymer solutions and liquid crystals are constituted by mesoscopic entities held together by weak forces. Their mechanical moduli are several orders of magnitude lower than those of atomic solids. The application of small to moderate stresses to these materials results in the disruption of their microstructures. The resulting flow is non-Newtonian and is characterised by features such as shear rate-dependent viscosities and non-zero normal stresses. This article begins with an introduction to some unusual flow properties displayed by soft matter. Experiments that report a spectrum of novel phenomena exhibited by these materials, such as turbulent drag reduction, elastic turbulence, the formation of shear bands and the existence of rheological chaos, flow-induced birefringence and the unusual rheology of soft glassy materials, are reviewed. The focus then shifts to observations of the liquid-like response of granular media that have been subjected to external forces. The article concludes with examples of the patterns that emerge when certain soft materials are vibrated, or when they are displaced with Newtonian fluids of lower viscosities.