Tunable discontinuous shear thickening in capillary flow of MR suspensions

TL;DR

This paper investigates the shear thickening behavior of highly concentrated iron particle suspensions in capillary flow, demonstrating controllable jamming transitions influenced by magnetic fields, with implications for damping and force control applications.

Contribution

It reveals the presence of a reversible jamming transition in capillary flow of iron suspensions, controllable via magnetic fields, expanding understanding of shear thickening in confined geometries.

Findings

Discontinuous shear thickening observed in capillary flow.

Magnetic field controls the formation of a porous jammed medium.

Reversibility of jamming transition enables potential applications.

Abstract

Very concentrated suspensions of iron particles in water or ethylene glycol can be obtained thanks to the use of superplasticizer molecules used in cement industry. At high volume fractions, these suspensions show a discontinuous shear thickening which was thoroughly characterized in rotational geometries. We will show that the jamming transition is also present in a capillary flow, and that it manifests through the formation of a non-consolidated porous medium at the constriction between the barrel and the capillary. In suspension of iron particles, the dynamics of formation of this porous medium, and so the pressure, can be controlled by a low magnetic field and is reversible for a constant volume flow rate, opening potential new applications in the domain of dampers and force control devices.