[Terminology] Plastic fluid (Bingham plastic fluid)
Non-Newtonian fluid.
Not obey Newton’s law of viscosity.
Relationship of D(shear velocity) - τ(shear stress): there is a point of intersection with shear stress axis; value of the point is yield value τy.
Only when the shear stress τ is greater than the yield value τy, fluid flows.
When the shear stress τ is greater than the yield value τy, there are the following fluids states:
1 Ordinary plastic fluid
Obey Newton’s law of viscosity.
Relationship of D(shear velocity) - τ(shear stress) is straight line, but does not pass through the origin.
τ-τy=ηD
Common ordinary plastic fluids have toothpaste, paint and so on.
2 Nonlinear plastic fluid
Not obey Newton’s law of viscosity.
(1) Herschel-Bulkley fluid
Rheological properties obey exponential relationship.
τ-τy=KDn