What is the difference between sharp-crested and broad-crested weirs?

Sharp-crested weirs have thin edges producing critical flow. Broad-crested weirs have wide horizontal crests; flow is subcritical upstream and critical at the crest.

When should I use a V-notch vs rectangular weir?

V-notch weirs are more accurate for small flows because the notch angle concentrates low flows. Rectangular weirs handle larger flows better.

How does head H affect weir discharge?

For rectangular weirs Q ∝ H^1.5, for V-notch Q ∝ H^2.5. Small head measurement errors have larger effects on V-notch weirs at high flows.

Weir Flow Calculator

Calculate discharge over weirs: sharp-crested rectangular Q = 1.84·L·H^1.5, V-notch 90° Q = 1.38·H^2.5. Used for flow measurement in rivers, canals, and stormwater channels.

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 discharge over weirs: sharp-crested rectangular Q = 1.84·L·H^1.5, V-notch 90° Q = 1.38·H^2.5. Used for flow measurement in rivers, canals, and stormwater channels. Use the weir flow result to inform your clinical assessment.

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Frequently Asked Questions

What is the difference between sharp-crested and broad-crested weirs?

When should I use a V-notch vs rectangular weir?

How does head H affect weir discharge?