Multi-Axial Magnetic Field RHEology

The full rheological response of magnetorheological (MR) fluids will be investigated under unsteady multiaxial magnetic fields for the first time. Such fields are able to drive the MR fluid to minimum energetic states.

Thus, we hypothesize that the superposition of multiaxial fields will constitute a relatively easy and straightforward mechanism to optimize MR fluid performance (contrary to current optimization routes, mainly based on complex schemes to tailor MR fluid constituents). The project will assess the MR fluid behavior in both pre-yield and post-yield regimes.

In the two cases, bulk rheological properties (viscoelastic moduli, viscosity and normal stresses) will be investigated in terms of the particle microscale structure and dynamics, formation of percolating particle networks at rest or (expected) lamellar structures under steady flow. To do so, the problem will be tackled firstly from a numerical point of view at the Partner Organization.

MR fluids will be modelled implementing direct contact forces between particles, hydrodynamics and unsteady magnetic multiaxial interactions using Molecular and Stokesian Dynamics.

Secondly, the results from these computational studies will be corroborated through experiments at the Hosting Institution using a custom-built high-speed confocal magneto-rheomicroscope.

This consists of a high-speed confocal rheomicroscope coupled to a unique magnetic field generator that allows, at the same time, visual access to the sample and the generation of unsteady multiaxial fields.

With this novel and comprehensive project, it is intended to open a new branch in the magnetorheology research field, testing the ability of multiaxial fields to improve MR performance and promote their exploitation in novel or current applications.