Non-Newtonian fluids, time dependent

The viscosity of the fluid is dependent on temperature, shear rate and time.

Depending on how viscosity changes with time the flow behaviour is characterised as:
  • thixotropic    (time thinning, i.e. viscosity decreases with time)
  • rheopectic    (time thickening, i.e. viscosity increases with time)

Thixotropic fluids are quite common in chemical as well as in food industry. Rheopectic fluids are very rare.

Note: some fluids show time thinning behaviour due to breakdown of structure. This phenomenon is sometimes known as rheomalaxis.

  • thixotropic: yoghurt, paint
  • rheopectic: gypsum paste

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Non-Newtonian time independent fluids
Non-Newtonian time dependent fluids

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