# Difference between revisions of "Reynolds number"

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Reynolds numbers are used to characterize different flow regimes, such as laminar or turbulent flow: laminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion, while turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce random [[Eddy (fluid dynamics)|eddies]], [[Vortex|vortices]] and other flow instabilities. Reynolds numbers can be greatly varied depending on the temperature of fluids, viscosity, and also the elevation at which the experiment is conducted. | Reynolds numbers are used to characterize different flow regimes, such as laminar or turbulent flow: laminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion, while turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce random [[Eddy (fluid dynamics)|eddies]], [[Vortex|vortices]] and other flow instabilities. Reynolds numbers can be greatly varied depending on the temperature of fluids, viscosity, and also the elevation at which the experiment is conducted. | ||

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+ | [[Viscoelastic scales#Reynolds number|Reynolds number]] in [[Viscosity, elasticity, and viscoelasticity]] from [[Main Page#Lectures for AP225|Lectures for AP225]]. |

## Revision as of 15:53, 27 November 2011

The Reynolds number <math>\mathrm{Re}</math> is a dimensionless quantity that gives a measure of the ratio of inertia forces <math> \left( \rho {\bold \mathrm V}^2 \right) </math> to viscous forces <math> \left( {{\mu {\bold \mathrm V}} \over {L}} \right)</math> and therefore quantifies the relative importance of these two types of forces for given flow conditions.

Reynolds numbers are used to characterize different flow regimes, such as laminar or turbulent flow: laminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion, while turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce random eddies, vortices and other flow instabilities. Reynolds numbers can be greatly varied depending on the temperature of fluids, viscosity, and also the elevation at which the experiment is conducted.

See also:

Reynolds number in Viscosity, elasticity, and viscoelasticity from Lectures for AP225.