Steady shear rate rheology of suspensions, as described by the giant floc model.
The break-down of a particle network by shear is described as the development of shear planes: a region able to withstand low shear stresses may break down under a larger stress; thus with increasing shear stress and shear rate, the mutual distance (A) between successive shear planes decreases until, at very high shear rates, A approaches the particle diameter. The shear planes are idealised as flat planes. Energy dissipation during shear is predominantly due to the energy dissipated through the movement of the particles; the energy dissipation due to breakage and renewed formation of bonds between particles is relatively small. A consideration of the energy dissipated during the encounters of particles during shear, including that dissipated by entrained particles, then leads to a relation between this energy dissipation and the average fraction L, over which a moving particle entrains a neighbour. L includes the effect of parts of the network which are rotating under the influence of the shear. In the limit of large shear rates, L is found to depend only to a small extent on whether the suspension is coagulated or not.
Stein
H N
HN
Laboratory of Colloid Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands. tgttrf@chem.tue.nl
Laven
J
J
D008956:Models, Chemical; D012212:Rheology; D013314:Stress, Mechanical