Outdoors & maps
Open-channel Froude number
Compare flow speed with the shallow-water gravity-wave scale.
A clear answer. Here’s how.
Uses Fr=V/sqrt(gD), with hydraulic depth D equal to flow area divided by free-surface top width. Reports subcritical below 1, supercritical above 1 and critical within 10⁻⁸ of 1. Hydraulic depth is not generally hydraulic radius or maximum depth. This is a one-dimensional gravity-flow descriptor, not a hydraulic-jump or flood model.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Mean speed (m/s)
- 2
- Hydraulic depth A/top-width (m)
- 0.5
Example result
- Froude number
- 0.903201511504
- Open-channel regime
- Subcritical