Froude Number

An introduction to and a definition of the Froude Number

The Froude Number is a dimensionless parameter measuring of the ratio of the inertia force on a element of fluid to the weight of the fluid element - the inertial force divided by gravitational force.

The Froude Number can be expressed as

Fr = v / (g l)1/2         (1)


Fr = Froude number

v = velocity

g = gravity

l = characteristic length

The Froude Number is relevant in fluid dynamic problems where the weight of the fluid is an important force.

In general this is the situation for free surfaces like cold windows and hot radiators. It is used in momentum transfer in general and open channel flow and wave and surface behavior calculations in particular.

The Froude Number is also important in analyzing flow in spillways, weirs, channel flows, rivers and ship design.

Related Topics

  • Fluid Mechanics - The study of fluids - liquids and gases. Involves various properties of the fluid, such as velocity, pressure, density and temperature, as functions of space and time.

Related Documents

Tag Search

  • en: Froude number definition

Search the Engineering ToolBox

- "Search is the most efficient way to navigate the Engineering ToolBox!"

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your SketchUp model with the Engineering ToolBox - SketchUp Extension/Plugin - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro. Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Translate the Engineering ToolBox!
About the Engineering ToolBox!