What are the flow formulas for different weir types?

Rectangular (Francis formula): Q = 1.84 × L × H^1.5; 90° V-notch (Thomson): Q = 1.38 × H^2.5; Cipolletti trapezoidal: Q = 1.86 × L × H^1.5. Where L is weir length (m) and H is head above weir crest (m). All per ISO 1438 for open channel flow measurement.

What are the limitations of the sharp-crested weir formula?

The Francis formula is valid for H 0.06 m (below this, surface tension affects results), and weir height P > 2H (ensures fully aerated nappe). For partially contracted weirs, apply the Rehbock correction per ISO 1438.

Sharp-Crested Weir Flow Rate Calculator

Calculate flow rate over rectangular, V-notch (triangular), and trapezoidal sharp-crested weirs for open channel flow measurement.

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 flow rate over rectangular, V-notch (triangular), and trapezoidal sharp-crested weirs for open channel flow measurement. Use the sharp-crested weir result to inform your clinical assessment.

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Frequently Asked Questions

What are the flow formulas for different weir types?

What are the limitations of the sharp-crested weir formula?