My answer to What is basic difference between viscosity and plastic viscosity?
Answer by Arûn Râinâ:
The viscosity of ais a measure of its to gradual deformation by or .
For liquids, it corresponds to the informal concept of "thickness". For example,has a much higher viscosity than .
Viscosity is a property arising from collisions between neighboring particles in a fluid that are moving at different. When the fluid is forced through a tube, the particles which compose the fluid generally move more quickly near the tube's axis and more slowly near its walls: therefore some , (such as a difference between the two ends of the tube), is needed to overcome the friction between particle layers to keep the fluid moving. For the same velocity pattern, the stress required is proportional to the fluid's viscosity.
The word "viscosity" is derived from the"viscum", meaning and also a viscous made from mistletoe berries
Apparent viscosity (sometimes denoted η)is theapplied to a fluid divided by the (
For a, the apparent viscosity is constant, and equal to the Newtonian viscosity of the fluid, but for , the apparent viscosity depends on the shear rate. Apparent viscosity has the Pa·s ( – , but the is frequently used in practice: (1 mPa·s = 1 cP).