RHEOLOGICAL CHARACTERISATION OF COMPLEX FLUIDS

IN ELECTRO-MAGNETIC FIELDS

Corneliu Balan¹, Ladislau Vekas², Eugen Gheroghiu³

1 REOROM Laboratory, Hydraulics Department, Politehnica

University of Bucharest, Romania, (corresponding author, balan@hydrop.pub.ro)

2 NCESCF, Politehnica University of Timisoara, Romania

3 International Center of Biodynamics, Bucharest, Romania

The paper is dedicated to the rheological investigation and modeling of complex fluids behavior in the presence of electro-magnetic fields (the samples are crude oilswater emulsions enriched with ferrofluids and normal blood). The study is focused on the determination of the electro-magneto-rheological properties of the samples, respectively: (i) measurement of magnetic permeability, electric permittivity and conductivity, (ii) modeling the magnetic field influence on samples viscosity (the start-up of simple shear motion in presence of magnetic field, applied normal to the direction of velocity). Our results include the tested samples in the category of thixotropic, viscoelastic, paramagnetic and semi-conductor fluids. The experiments, corroborated with numerical simulation of the process, put in evidence the capability of electromagneto-rheology to produce value information, both on the micro-scale formulation of complex fluid and on the flow dynamics at the macro-scale. In particular: (i) viscosity sensitivity on magnetic field intensity and variation of electric permittivity might be correlated with changes in the local flow kinematics, (ii) differences between samples chemical formulation and rheology (asphalt and paraffin based crude oils, respectively) correspond to differences of their electro-magnetic properties. The present results have the potential applicability in building a special device to investigate non-invasively the flow structure of complex fluids in micro-geometries.