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| it is said to be a 'newtonian' fluid. Non-newtonian fluids exhibit a variation of viscosity depending on | it is said to be a 'newtonian' fluid. Non-newtonian fluids exhibit a variation of viscosity depending on | ||
| ] within the flow field, the history that a fluid 'particle' experiences on its flow | ] within the flow field, the history that a fluid 'particle' experiences on its flow | ||
| path, etc. If the viscosity of a fluid |
path, etc. If the viscosity of a fluid depends solely on the gradients within the flow field it is called | ||
| generalized newtonian or purely newtonian. | generalized newtonian or purely newtonian. | ||
Revision as of 06:41, 16 July 2002
Viscosity is a property of fluids describing its internal resistance to flow and may be thought of as a measure of fluid friction. Rheology is the field of science that deals with viscosity.
If the viscosity of a fluid is constant (neglecting temperature and pressure effects) it is said to be a 'newtonian' fluid. Non-newtonian fluids exhibit a variation of viscosity depending on gradients within the flow field, the history that a fluid 'particle' experiences on its flow path, etc. If the viscosity of a fluid depends solely on the gradients within the flow field it is called generalized newtonian or purely newtonian.
The viscosity of fluids is either given as dynamic viscosity η (Pa.s = kg/m/s) or as kinematic viscosity ν (m^2/s). Both terms are related via the fluid density ρ to each other: η = ν * ρ.
Some dynamic viscosities of (newtonian) fluids are listed below:
- acetone 0.33*10 Pa.s
- methanol 0.59*10 Pa.s
- water 1.0*10 Pa.s
- nitrobenzol 2.0*10 Pa.s
- sulfuric acid 30*10 Pa.s
- olive oil 81*10 Pa.s
- ricinus oil 985*10 Pa.s
- glycerin 1485*10 Pa.s
Contrary to many assertions, glass is an amorphous solid, not a liquid, and it does not flow. See the article on glass for more details on this.
Many fluids like honey have a wide range of viscosity.