Discharge Over Rectangle Weir Considering Bazin's Formula Calculator

Bazin's Formula:

\[ Q = \left(0.405 + \frac{0.003}{H}\right) \times L_w \times \sqrt{2 \times g} \times H^{3/2} \]

Discharge Weir (Q):

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1. What is Bazin's Formula for Rectangular Weirs?

Bazin's formula is an empirical equation used to calculate the discharge over a rectangular weir. It accounts for the head of liquid above the weir crest and the length of the weir, providing a more accurate estimation of flow rate than simpler formulas.

2. How Does the Calculator Work?

The calculator uses Bazin's formula:

\[ Q = \left(0.405 + \frac{0.003}{H}\right) \times L_w \times \sqrt{2 \times g} \times H^{3/2} \]

Where:

\( Q \) — Discharge over weir (m³/s)
\( H \) — Head of liquid above weir crest (m)
\( L_w \) — Length of weir (m)
\( g \) — Gravitational acceleration (9.80665 m/s²)

Explanation: The formula incorporates a correction factor (0.405 + 0.003/H) that accounts for the velocity of approach and other hydraulic characteristics of flow over a rectangular weir.

3. Importance of Weir Discharge Calculation

Details: Accurate discharge calculation is essential for hydraulic engineering applications, including flow measurement in open channels, irrigation systems, and water treatment facilities.

4. Using the Calculator

Tips: Enter the head of liquid in meters and the length of weir in meters. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of applicability for Bazin's formula?
A: Bazin's formula is generally applicable for rectangular weirs with heads between 0.05m and 0.6m, and for weirs with sufficient approach velocity conditions.

Q2: How does Bazin's formula differ from other weir formulas?
A: Bazin's formula includes an empirical correction factor that makes it more accurate than the basic Francis formula, particularly for smaller heads and specific weir configurations.

Q3: What are the limitations of Bazin's formula?
A: The formula may be less accurate for very small heads, submerged weirs, or weirs with significant approach velocity variations.

Q4: Can this formula be used for other weir shapes?
A: No, Bazin's formula is specifically designed for rectangular weirs. Other formulas exist for triangular, trapezoidal, and other weir shapes.

Q5: How important is the gravitational constant in the calculation?
A: The gravitational constant is crucial as it determines the theoretical velocity of flow. Using the standard value of 9.80665 m/s² ensures consistent results.