In fluid dynamics, the Chézy formula describes the mean flow velocity of steady, turbulent open channel flow :

where

The formula is named after Antoine de Chézy, the French hydraulics engineer who devised it in 1775.

Usage with Manning coefficient

This formula can also be used with Manning's Roughness Coefficient, instead of Chézy's coefficient. Manning derived the following relation to C based upon experiments:

where

  • is the Chézy coefficient [m½/s],
  • is the hydraulic radius, which is the cross-sectional area of flow divided by the wetted perimeter (for a wide channel this approximately equal to the water depth) [m], and
  • is Manning's roughness coefficient.

Both formulae are empirical, but the Manning formula is widely accepted as more accurate and is the base formula still in current use for all open channel flow analysis.


This article uses material from the Wikipedia article Chézy formula, which is released under the Creative Commons Attribution-Share-Alike License 3.0.