Phenomenological model for ordered onions under shear flow

TL;DR

This paper introduces a phenomenological model to simulate the formation and phase transition of multi-lamellar vesicles (onions) under shear flow, capturing size changes and order-disorder transitions in surfactant systems.

Contribution

It presents a novel model that reproduces ordered and disordered onion phases and analyzes critical factors driving phase transitions under shear flow.

Findings

Model successfully simulates onion size and phase transitions.

Identifies key factors influencing order-disorder transition.

Numerical results match experimental observations.

Abstract

We propose a phenomenological model for the multi-lamellar vesicles (onions) formation induced by shear flow. In a nonionic surfactant (C$_{12}$E$_4$) system, onion phases under a fixed shear flow within a certain range show the order-disorder transition accompanied with a size jump by changing temperature. Our model can simulate ordered and disordered onion phases with different onion sizes. We show numerical results of the onion formation simulated by the model and also discuss what factors in this system are critical to cause the transition between these two different onion phases.