Suppression of the Rayleigh-Plateau instability on a vertical fibre coated with wormlike micelle solutions

TL;DR

This study demonstrates that surfactant solutions with shear-induced structures can suppress the Rayleigh-Plateau instability on a vertical fibre, with stabilization depending on viscoelastic properties and film thickness.

Contribution

It is the first to show stabilization of the Rayleigh-Plateau instability using surfactant solutions with shear-induced structures and provides a model linking elasticity to stability.

Findings

Shear-induced structures are necessary for stabilization.

Elastic modulus above a critical value prevents instability.

The method estimates bulk elasticity of shear-induced states.

Abstract

We report on the Rayleigh-Plateau instability in films of giant micelles solutions coating a vertical fibre. We observe that the dynamics of thin films coating the fibre could be very different from the Newtonian or standard Non-Newtonian cases. By varying the concentration of the components of the solutions and depending on the film thickness, we show for the first time that the Rayleigh-Plateau instability can be stabilized using surfactant solutions. Using global rheology and optical visualisations, we show that the development of shear-induced structures is required to stabilize the micellar film along the fibre. Assuming that the viscoelastic properties of the shear-induced state can be described by a simple model, we suggest that, in addition to the presence of shear-induced structures, the latter must have an elastic modulus greater than a critical value evaluated from a linear stability analysis. Finally, our analysis provides a way of estimating the bulk elasticity of the shear-induced state.