While two flows with approximately equal Re can behave quite differently in practice due to their chaotic nature in which even small differences in shape and surface roughness can produce very different flows, the Reynolds number is still a useful and widely used guide to flow similarity. Edgy currents, in turn, use up energy and may produce cavitation. Turbulence also leads to edgy currents in which different sub-flows intersect or even move counter to the overall flow direction. One interprets the Reynolds number as such: a low Reynolds number suggest the flow should be dominated by laminar (sheet-like) flow at high Reynolds numbers one expects significant turbulence due to the differences in the fluid's speed and direction. At larger scale it has uses in meteorology and climatology. In practical applications the ability to predict when a turbulent flow will appear is important in designing piping systems, airplane wings, aerodynamic vehicles, including for scaling from study models to actual aircraft/vehicle. It can also be used to study and predict hot gases as in a flame in air. The number sees uses in fluid mechanics where it is used to predict flow patterns in different fluid flow scenarios. Knowing Re one can anticipate the transition from laminar to turbulent flow which is the main utility of a Reynolds Number calculator. The Reynolds number (Re) is a dimensionless quantity for dynamic similarity and is calculated as the ratio of inertial forces to viscous forces of a flow of liquid. The Reynolds Number calculator will then apply the relevant equation and produce the Reynolds Number (Re) as result. compressible gases) and fluids of variable viscosity (non-Newtonian fluids). Special consideration should be taken for fluids of variable density (e.g. the inner diameter of a pipe, the diameter of a sphere moving in liquid, or the length of a plate over which the substance is flowing. Finally, enter the characteristic length, e.g. Then enter the velocity at which the substance is moving. m 2/s, Stokes and centiStokes for kinematic viscosity, imperial and metric/scientific units for density, velocity and length).įirst, select whether you know the substance's kinematic viscosity or the dynamic viscosity and density and then enter the quantities you know. It supports a wide range of input and output measurement units (e.g. The conversion of conventional measures into cSt is inaccurate, particularly within the 1 to 9.5 cSt range (see DIN 1342, viscosity of NEWTONian liquids).With the help of this calculator you can compute the Reynolds Number of a liquid or gas. If values higher than 1000 cSt are required, the data given from 60 cSt can be multiplied accordingly by 10, 100, 1000 etc. The table can also alternatively be used to assign corresponding values to one another. The former units are no longer approved and can be converted to m²/s using Fig. To ensure correct usage, the Stokes units and the units still currently in general use must be converted into the SI unit m 2/s. These are: degrees Engler (✮) in Germany, Saybolt seconds (S˝) in USA and Redwood seconds (R˝) in Britain. The conventional units of viscosity are unsuitable as a basis for calculation, but are still used in commerce. The Stokes unit ceased to be officially valid in 1978. The hundredth part thereof is a Centi stokes (cSt). The unit used here is m 2/s and is called – in honour of the Irish physicist STOKES – a Stokes (St). However, most measurements are still made in centistokes, e.g. Thus water at 20 ✬ has a kinematic viscosity ν = 1,002 Kinematic viscosity (ν) designates the quotient of the dynamic viscosity of the fluid handled and its density.
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