Shear-thickening induced by Faraday waves in dilute wormlike micelles

TL;DR

This study demonstrates that Faraday surface waves can induce shear-thickening in dilute wormlike micelle solutions, significantly increasing viscosity and delaying instability onset through surface vibration effects.

Contribution

It introduces a novel link between Faraday wave-induced surface vibrations and shear-thickening behavior in micellar solutions, supported by a quantitative model.

Findings

Surface waves increase fluid viscosity during oscillation.

Pre-shaking delays the Faraday instability onset.

A time-dependent viscosity model explains the observations.

Abstract

We investigate the effect of surface waves generated by the Faraday instability on a shear-thickening surfactant solution under vertical vibrations. We show that a prolonged oscillation of the surface above the instability onset leads to an increase of the fluid viscosity. This phenomenon is evidenced by comparing the time needed for the instability to develop in the fluid at rest and once the fluid has been shaken above onset: pre-shaking may delay the instability by two orders of magnitude. A simple model based on a time-dependent viscosity is proposed which accounts quantitatively for the experimental observations.