How is the Froude number calculated for open channel flow?

Fr = V / √(g×D_h), where V is average velocity (m/s), g = 9.81 m/s², and D_h is hydraulic depth = A/T (flow area divided by top water surface width). Fr 1 = supercritical (rapid) flow.

What is critical depth and why is it important?

At critical depth, the Froude number equals 1 and specific energy is minimum for a given discharge. Critical depth y_c for a rectangular channel = (q²/g)^(1/3), where q = Q/b (discharge per unit width). Critical depth control points (weirs, flumes) are used for flow measurement because discharge is a unique function of depth.

Froude Number (Open Channel) Calculator

Calculate the Froude number to determine whether open channel flow is subcritical, critical, or supercritical, and find critical depth.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Calculate the Froude number to determine whether open channel flow is subcritical, critical, or supercritical, and find critical depth. Use the froude number result to inform your clinical assessment.

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Frequently Asked Questions

How is the Froude number calculated for open channel flow?

What is critical depth and why is it important?