Shearing
In rheology, shearing of a substance is the key to knowledge of flow
behaviour and structure. A sheared flow is achieved through flow between
parallel planes, rotational flow between coaxial cylinders where one cylinder
is stationary and the other one is rotating, telescopic flow through capillaries
and pipes, and torsional flow between parallel plates.
To enable study of the viscosity of a material, the shearing must induce
stationary flow of the material. The flow occurs through rearrangement and
deformation of particles and through breaking of bonds in the structure of
the material.