Atypical plug formation in internal elastoviscoplastic fluid flows over a non-smooth topology

TL;DR

This study combines experimental visualization and numerical simulations to analyze the flow behavior of elastoviscoplastic fluids over non-smooth geometries, revealing asymmetries linked to elasticity and plasticity effects.

Contribution

It introduces a combined experimental and computational approach to understand plug formation and asymmetry in elastoviscoplastic flows over complex topologies.

Findings

Plug shape asymmetry depends on Bingham and Weissenberg numbers.

Asymmetry results collapse onto a single curve when scaled appropriately.

Elasticity and plasticity interactions are key to flow behavior.

Abstract

An experimental and computational investigation of the internal flow of elastoviscoplastic fluids over non-smooth topologies is presented in two complimentary studies. In the first study, we visualize the creeping flow of a Carbopol gel over a cavity embedded in a thin slot using Optical Coherence Tomography (OCT) and confocal microscopy. We measure the size and shape of the plug as a function of Bingham and Weissenberg numbers. An asymmetry in the plug shape is observed which is also evident in our second study -- numerical simulations using adaptive finite element method based upon an augmented Lagrangian scheme. We quantify the asymmetry and present the results as a function of the product of the Weissenberg and Bingham numbers which collapse onto a single curve for each of these geometries. These findings underscore the theoretical underpinnings of the synergy between elasticity and plasticity of these complex fluids.