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Open Channel Flow Profile Simulator

Manning normal depth · Critical depth · Froude-number flow regime in a trapezoidal channel

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Subcritical Flow — Mild Slope

Subcritical flow (Fr<1) — Froude = 0.635. Flow is deep and slow; disturbances propagate upstream. Normal depth exceeds critical depth (yn > yc).

🌊 Flow & Channel Inputs

Discharge Q100 cfs

Bottom width b8 ft

Side slope z (z:1 H:V)2:1

Manning's n0.03

Longitudinal slope S0.005 ft/ft

📊 Results

Normal depth (yn)1.936 ft

Critical depth (yc)1.486 ft

Velocity at yn4.35 ft/s

Froude number (Fr)0.635

Flow area (A)22.98 ft²

Top width (T)15.74 ft

Hydraulic depth (Dh)1.46 ft

Flow regimeSubcritical (mild)

Method:Normal depth solves Manning's equation Q = (1.49/n)·A·R^(2/3)·√S by bisection. Critical depth solves Q²/g = A³/T. The Froude number Fr = V/√(g·A/T) classifies the regime: Fr<1 subcritical, Fr>1 supercritical, Fr≈1 critical.

Channel Cross-Section · Water at Normal Depth

Normal depth (yn) water surface

Critical depth (yc)