A fluid in which deformation is proportional to velocity gradients.

A fluid or dispersion whose rheological behavior is described by Newton's law of viscosity. Here shear stress is proportional to shear rate, with the proportionality constant being the viscosity.

a fluid in which the viscosity remains constant for all rates of shear if constant conditions of temperature and pressure are maintained. Most drilling fluids behave as non-Newtonian fluids, as their viscosity is not constant but varies with the rate of shear.

a fluid in which shear stress is linearly proportional to the velocity gradient

a viscous fluid whose shear stresses are a linear function of the fluid strain rate

A fluid in which the rate of shear is proportional to the shear force, e.g., water.

An incompressible fluid that remains unordered whilst flowing.

fluid whose viscosity does not change with rate of flow.

A fluid that does not change viscosity as it is agitated.

A fluid with a constant viscosity at a given temperature regardless of the rate of shear. Single-grade oils are Newtonian fluids. Multigrade oils are NON-Newtonian fluids because viscosity varies with shear rate.

A fluid whose viscosity is independent of shear rate. The term is useful in differentiating between thixotropic and dilatant fluids.

Compare with non-Newtonian fluid. A fluid whose viscosity doesn't depend on gradients in flow speed. Gases and low-molecular weight liquids are usually Newtonian fluids.

any liquid which behaves in a Newtonian manner (Shear stress is linearly proportional to shear rate and Viscosity is constant when shear rate changes) is said to be Newtonian.

A Newtonian fluid (named for Isaac Newton) is a fluid that flows like water—its stress / strain curve is linear and passes through the origin. The constant of proportionality is known as the viscosity.