A non-Newtonian fluid is a liquid whose flow properties are not described by a single constant value of viscosity. Examples of non-Newtonian fluids are: polymer solutions, starch suspensions, paint, blood, food products, and mining suspensions of densely packed particles.

The relation between the shear stress and the strain rate can be either linear or nonlinear. This means that, for fluids exemplifying a nonlinear characteristic, a constant coefficient of viscosity cannot be defined. FluidFlow allows you to describe this relationship of shear-dependent viscosity, according to any of the following rheology models:

    • Bingham Plastic
    • Power Law
    • Herschel-Bulkley
    • Casson

Power law modelling of rheology data

The example opposite shows viscometer data for a non-Newtonian fitted to a Power Law relationship.

FluidFlow3 uses different friction factor relationships for each available model, the relationships are valid over all flow regimes.