The Flow of Wormlike Micellar Gels in Narrow Capillaries

Wormlike micellar solutions formed by long-chained zwitterionic surfactants show gel-like rheology at room temperature and have recently been found to exhibit other complex and interesting rheological features. We study the capillary flow of these wormlike micellar gels in a canonical flow scenario using optical coherence tomography-based velocimetry and report the existence of plug flows with strong wall-slip along with non-parabolic velocity profiles with shear-layers for different surfactant concentrations and imposed flowrates. These experiments shed light on the fluid dynamics of wormlike micelles in simple geometries and inform ongoing attempts to understand the cross-talk between the rheology and flow of soft matter.