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Constitutive models of electrorheological and magnetorheological fluids using viscometers

2005; IOP Publishing; Volume: 14; Issue: 5 Linguagem: Inglês

10.1088/0964-1726/14/5/041

1361-665X

Young Choi, J U Cho, Seung‐Bok Choi, Norman M. Wereley,

Fluid Dynamics and Vibration Analysis

A key aspect of application of electrorheological (ER) and magnetorheological (MR) fluids is the characterization of rheological properties. In this study, two rotational viscometers to measure the field-dependent flow behavior (shear stress versus shear rate) of ER/MR fluids are theoretically analyzed. One is a rotational coaxial cylinder viscometer, and the other is a rotational parallel disk viscometer. The equations between shear stress and torque as well as shear rate and angular velocity are derived on the basis of the Bingham-plastic, biviscous, and Herschel–Bulkley constitutive models. The shear stress for the rotational coaxial cylinder viscometer can be straightforwardly calculated from the measured torque. However, in order to determine the shear rate, three approximation methods are applied. Meanwhile, the shear stress and shear rate in the rotational parallel disk viscometer can be obtained directly from the torque and angular velocity data. In order to comprehensively understand the flow behavior of ER/MR fluids with respect to the constitutive models, nondimensional analyses are undertaken in this study.