Simultaneous measurement of viscosity and kinetic temperature in a driven dense granular suspension
Seminar Room 1, Newton Institute
AbstractWe look at thermodynamic and rheological properties of a slowly-driven dense suspension of glass spheres ($D = 250\mu m$) in water. We do so using a torsional pendulum as a rheometer and we measure simultaneously the kinetic granular temperature using speckle visibility spectroscopy. We can control the density of the suspension very precisely in our region of interest (between $\phi = 0.5$ abd $\phi = 0.56$) by changing the flow rate and viscosity of the liquid used to fluidise the grains. A spherical torsional pendulum covered in glued grains is immersed in the suspension. It is driven at small angles to measure viscosity. Simultaneously, we use a laser speckle pattern created in transmission to measure the velocities of grains as a function of the degree of fluidisation, and thence obtain a measure of the kinetic temperature.
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