| Revision as of 08:19, 3 October 2002 edit217.168.172.202 (talk)mNo edit summary← Previous edit | Revision as of 08:20, 3 October 2002 edit undo217.168.172.202 (talk)mNo edit summaryNext edit → | ||
| Line 7: | Line 7: | ||
| ] 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 depends solely on the gradients within the flow field it is called | path, etc. If the viscosity of a fluid depends solely on the gradients within the flow field it is called | ||
| generalized |
generalized Newtonian or purely Newtonian. | ||
| The viscosity of fluids is either given as dynamic viscosity η | The viscosity of fluids is either given as dynamic viscosity η | ||
| Line 14: | Line 14: | ||
| Both terms are related via the ] ρ to each other: η = ν * ρ. | Both terms are related via the ] ρ to each other: η = ν * ρ. | ||
| Some dynamic viscosities of ( |
Some dynamic viscosities of (Newtonian) ] are listed below: | ||
| ] (at 0 ]): | ] (at 0 ]): | ||
Revision as of 08:20, 3 October 2002
Viscosity is a property of fluids describing their 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; viscosity is measured with a viscometer.
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
- castor 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.