Non-Newtonian fluid behaviour

One may classify fluids in two different ways; either according to their responseto the externally applied pressure or according to the effects produced under theaction of a shear stress. The first scheme of classification leads to the so called‘compressible’ and ‘incompressible’ fluids, depending upon whether or not thevolume of an element of fluid is dependent on its pressure. While compressibilityinfluences the flow characteristics of gases, liquids can normally beregarded as incompressible and it is their response to shearing which is ofgreater importance. In this chapter, the flow characteristics of single phaseliquids, solutions and pseudo-homogeneous mixtures (such as slurries, emulsions,gas–liquid dispersions) which may be treated as a continuum if theyare stable in the absence of turbulent eddies are considered depending upontheir response to externally imposed shearing action.
One may classify fluids in two different ways; either according to their response
to the externally applied pressure or according to the effects produced under the
action of a shear stress. The first scheme of classification leads to the so called
‘compressible’ and ‘incompressible’ fluids, depending upon whether or not the
volume of an element of fluid is dependent on its pressure. While compressibility
influences the flow characteristics of gases, liquids can normally be
regarded as incompressible and it is their response to shearing which is of
greater importance. In this chapter, the flow characteristics of single phase
liquids, solutions and pseudo-homogeneous mixtures (such as slurries, emulsions,
gas–liquid dispersions) which may be treated as a continuum if they
are stable in the absence of turbulent eddies are considered depending upon
their response to externally imposed shearing action.