Weber Number

Overview

The Weber number ($We$) is a dimensionless number comparing inertial forces to surface tension forces. It is important in droplet formation, bubble dynamics, and free surface flows.

Variables

Symbol	Description	Unit
$We$	Weber number	—
$\rho$	Fluid density	kg/m³
$v$	Flow velocity	m/s
$L$	Characteristic length	m
$\sigma$	Surface tension	N/m

Formula

$We = \frac{\rho v^2 L}{\sigma}$

Calculator

Notes

• Results are approximate and should be verified for critical applications
• Input values should be within reasonable engineering ranges

Formula

The Weber number is expressed as:

$We = \frac{\rho v^2 l}{\sigma}$

Applications

The Weber number is useful for analyzing flows where surface tension effects are significant. Its value indicates the relative importance of inertial forces versus surface tension forces.

• Droplet and Bubble Formation: Helps predict whether a liquid jet will break up into droplets.
• Thin Film Flows: Analyzes the stability and breakup of liquid films.
• Multiphase Flows: Characterizes the behavior of interfaces between different fluids, such as in atomization and spray processes.

References

• Original Source