Particle Image Velocimetry in Concentrated Suspensions: Application to Local Rheometry

Description

This paper presents an experimental facility that allows simultaneous viscosimetric and Particle Image velocimetry measurements on concentrated suspensions in a wide-gap Couette rheometer. The experimental procedure is detailed: the optical characteristics of the index-matched suspension are carefully studied, the bottom end effect on both the viscosimetric measurements and the recorded velocity profiles are analysed. First the experimental procedure is tested on a Newtonian fluid whose viscosity is known. The spatial and time resolutions of our device are shown to be 200µm and 100ms respectively. The precision of the local viscosity measurement is evaluated to better than 4%. Then we show that the device can be used to characterize the rheological behaviour of a 47%-concentrated suspension of 30 µ m spheres. According to the particles large size, the Brownian motion can be neglected. However, colloidal interaction are still noticeable.

Abstract

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