Thixotropic flow past a cylinder

TL;DR

This study investigates the flow behavior of a thixotropic fluid around a cylinder using a structural viscoplastic model, revealing how flow characteristics can be controlled by rheological parameters at moderate Reynolds numbers.

Contribution

It introduces a numerical analysis of thixotropic flow around a cylinder using a Bingham-based model with Papanastasiou regularisation, highlighting parameter effects.

Findings

Flow recirculation observed behind the cylinder.

Viscous flow properties can be modulated by rheological parameters.

Flow remains steady without vortex shedding at Re=45.

Abstract

We study the flow of a thixotropic fluid around a cylinder. The rheology of the fluid is described by means of a structural viscoplastic model based on the Bingham constitutive equation, regularised using the Papanastasiou regularisation. The yield stress is assumed to vary linearly with the structural parameter, which varies from zero (completely broken structure) to one (fully developed skeleton structure), following a first-order rate equation which accounts for material structure break-down and build-up. The results were obtained numerically using the Finite Element Method. Simulations were performed for a moderate Reynolds number of 45, so that flow recirculation is observed behind the cylinder, but vortex shedding does not occur. The effects of the Bingham number and of the thixotropy parameters are studied. The results show that the viscous character of the flow can be controlled within certain limits through these parameters, despite the fact that the Reynolds number is fixed.