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# Weber Number

## The Weber Number may be useful when analyzing fluid flows where there is an interface between two different fluids.

The Weber Number is a dimensionless value useful for analyzing fluid flows where there is an interface between two different fluids.

The Weber Number is the ratio between the inertial force and the surface tension force and the Weber number indicates whether the kinetic or the surface tension energy is dominant. It can be expressed as

We = ρ v2 l / σ                                              (1)

where

We = Weber number (dimensionless)

ρ = density of fluid (kg/m3, lb/ft3)

v = velocity of fluid (m/s, ft/s)

l = characteristic length (m, ft)

σ = surface tension (N/m)

Since the Weber Number represents an index of the inertial force to the surface tension force acting on a fluid element, it can be useful analyzing thin films flows and the formation of droplets and bubbles.

## Related Topics

• ### Fluid Mechanics

The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.

## Related Documents

• ### Dimensionless Numbers

Physical and chemical dimensionless quantities - Reynolds number, Euler, Nusselt, and Prandtl number - and many more.
• ### Surface Tension

Surface tension of liquids like water, mercury, oils and more.
• ### Surface Tension - Water in contact with Air

Surface tension of water in contact with air for temperatures ranging 0 to 100 degC (32 to 212 degF) - in imperial units (BG units) and SI units.
• ### Technical Terms in Fluid Mechanics

Some commonly used technical terms in fluid mechanics.

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## Citation

• The Engineering ToolBox (2004). Weber Number. [online] Available at: https://www.engineeringtoolbox.com/weber-number-d_583.html [Accessed Day Month Year].

Modify the access date according your visit.

8.21.8

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