D. Prasad et Hk. Kytomaa, PARTICLE STRESS AND VISCOUS COMPACTION DURING SHEAR OF DENSE SUSPENSIONS, International journal of multiphase flow, 21(5), 1995, pp. 775-785
This study describes the transition between the quasi-static and the v
iscous regimes of shearing of thin layers of spheres in a viscous flui
d at high solid loadings. Experiments were conducted in a Couette-type
shear cell in two complementary modes: (a) constant particle normal s
tress, variable solid fraction and (b) constant solid fraction, variab
le particle normal stress. During steady shearing under the constraint
of constant solid fraction, transition from a strain rate independent
stress to one with a linearly dependent behavior was found to occur w
ith a local minimum in the stresses with respect to strain rate; corre
spondingly, the solid fraction assumed a maximum with respect to strai
n rate under conditions of constant normal stress. These are the first
observations of such a phenomenon, which we call viscous compaction.
At sufficiently high strain rates, the mixture exhibited a linear Newt
onian-like scaling between strain rate and both shear and normal stres
ses. These measurements of normal stress are the first since those of
Bagnold.