Top: Size distribution of the particles used for the suspensions. (a) Dynoseeds TS-40 ( ) and (b) Dynoseeds TS-140 ( ). Bottom: Ellipticity of the particles. Smaller axis a as a function of the larger axis b normalized with the average particle diameter. (c) Dynoseeds TS-40 ( ) and (d) Dynoseeds TS-140 ( ). The average aspect ratios a/b are equal to 0.924 for the TS-40 and to 0.927 for the TS-140.
Rheometry: In a 50 mm parallel plate geometry, (a) viscosity of the pure fluid as a function of the shear rate . Measurements have been performed at ; (b) viscosity of the suspension as a function of the particle volume fraction, for and . The continuous line corresponds to a Krieger–Dougherty law [Krieger (1972)]: , with .
Sketch of the Taylor–Couette cell.
Lubrication pressure, calculated in the pure liquid of viscosity , for an axis misalignment and for (- -) , ( ) , (- ) , and the angular gap variation (—) (left axis). Note the cancellation of the lubrication pressure at fixed when averaged over the two directions of rotation.
(- -) Ramp of shear rate (right hand axis) against time (s) and (—) pressure transducer signal (left hand axis) measured (a) behind one grid and (b) (—) behind one impermeable membrane, for a suspension of particles of diameter at volume fraction .
(a) Image of the experimental cell with a suspension of TS-140 of volume fraction for taken 10 s after the beginning of the shear. (b) Spatiotemporal diagram built by plotting the light intensity of a vertical line along time (horizontal direction). The white strip on the top of the suspension corresponds to a “cream” of particles that have been ejected from the suspension due to shear.
Evolution of the grid (a) and membrane (b) pressure as a function of the shear rate for a suspension with volume fraction . ( ) Dynoseeds TS-40, ( ) Dynoseeds TS-140. The two dashed lines correspond to the asymptotic values of the pressure (i.e., 540 Pa for TS-140 and 1050 Pa for TS-40).
Evolution of the dimensionless grid (a) and membrane (b) pressure as a function of the particle volume fraction. Pressures are normalized by . ( ) Dynoseeds TS-40 and ( ) Dynoseeds TS-140. The insets display in logarithmic scale the pressures normalized with the shear stress of the suspension ( ).
Variation of the normalized (relative to the shear stress of the pure liquid) second normal suspension stress difference , with the volume fraction . ( ) Dynoseeds TS-40, ( ) Dynoseeds TS-140, (+) Yeo and Maxey (2010) , ( ) Sierou and Brady (2002) , ( ) Zarraga et al. (2000) , ( ) Singh and Nott (2003) , and ( ) Couturier et al. (2011) .
Comparison of , normalized with the fluid shear stress, , with the expression for the particle pressure, (see text).
Article metrics loading...
Full text loading...