# Borda–Carnot equation (for open channel flows)

## Description

In fluid dynamics the Borda–Carnot equation is an empirical description of the mechanical energy losses of the fluid due to a (sudden) flow expansion. The Borda–Carnot loss equation is only valid for decreasing velocity, v1 > v2, otherwise the loss ΔE is zero – without mechanical work by additional external forces there cannot be a gain in mechanical energy of the fluid. For open channel flows the fluid’s mechanical energy loss is related to the total head loss. The pressure acts effectively as a form of potential energy.

Related formulas## Variables

Δ_{E} | The fluid's mechanical energy loss per unit of fluid volume (J/m^{3}) |

ρ | Density of the fluid (kg/m^{3}) |

g | Standard gravity |

Δ_{H} | The total head loss (m) |