Open Channel Flow: Non-Uniform Flow

Flow where depth varies along the channel.

Specific Energy ($E$)

Energy per unit weight relative to the channel bottom.

$E = y + \frac{V^2}{2g} = y + \frac{Q^2}{2gA^2}$

Critical Flow

The flow state where specific energy is minimum for a given discharge. Froude Number ($Fr$): $Fr = \frac{V}{\sqrt{gy}}$

• $Fr = 1$: Critical Flow
• $Fr < 1$: Subcritical (Tranquil) Flow
• $Fr > 1$: Supercritical (Rapid) Flow

Critical Depth ($y_c$) for Rectangular Channel: $y_c = \sqrt[3]{\frac{q^2}{g}}$

• $q = Q/b$ (discharge per unit width)

Hydraulic Jump

A phenomenon where flow transitions abruptly from supercritical to subcritical, resulting in energy dissipation and a rise in water surface.

$\frac{y_2}{y_1} = \frac{1}{2} (\sqrt{1 + 8Fr_1^2} - 1)$

Solved Problems