•    The fluid in which the shear stress is not directly proportional to the rate of shear strain or velocity gradient, is called as Non-Newtonian Fluid.

e.g. Slurries, tooth paste, gels, polymer solution paint, lubricant oils

•    The non-linear relationship between shear stress and the rate fo deformation is called as Non-Newtonian fluid.

  ζ  ≠ μ du / dv




•    The viscosity which is defined as the slopes shown in called as apparent viscosity.

Where n = flow behaviour index

Pseudo plastic or Fluid:

•    Fluid in which the apparent viscosity decreases with increasing deformation rate (n<1) is called as Pseudo plastic fluid.

•    Examples are slurries, mud, polymer solution, gums, blood, milk, colloidal suspensions paper pulp in water.

ζ = μ (du / dy)ⁿ

Dilatants or Fluid:

•    Fluid in which the apparent viscosity increases with increasing deformation rate (n>1) is called as dilatants fluids.
e.g. Suspension of sand, starch, butter, sugar solution.

ζ = μ (du / dy)ⁿ

Bingham plastic Fluid or Ideal Plastic Fluid:

The fluid which possess a definite yield stress but then the relationship between shear stress and angular deformation is linear is called as Bingham plastic fluid.

ζ = ζ _y+ μ (du / dy)ⁿ

e.g. Sewage sludge, tooth paste, oil paint, jellies, applesauce, drilling mud.

Thyrotrophic Fluid or Plastic Fluid:

The fluid which possess a definite yield stress but then the relationship between shear and angular deformation is non-linear are called as Thixotrophic fluid. e.g. Printer ink, lipstick.

ζ = ζ _y+ μ (du / dy)ⁿ

Ideal Fluid:

The fluid which has zero viscosity or shear stress is always zero is called as ideal fluid, that’s why ideal fluid is represented by the horizontal axis.

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