1. What is Critical Depth in Open Channel Flow?

Critical depth in open channel flow is defined as the depth of flow where energy is at a minimum for a particular discharge. It represents the transition point between subcritical and supercritical flow regimes in open channels.

2. How Does the Calculator Work?

The calculator uses the critical depth formula:

Where:

• \( h_c \) — Critical depth (m)
• \( E_{min} \) — Minimum specific energy for open channel flow (m)

Explanation: The formula shows that critical depth is exactly two-thirds of the minimum specific energy required for open channel flow.

3. Importance of Critical Depth Calculation

Details: Calculating critical depth is essential for designing open channels, analyzing flow characteristics, determining flow regimes, and ensuring proper hydraulic structures design to prevent flooding or erosion.

4. Using the Calculator

Tips: Enter the minimum specific energy value in meters. The value must be positive and greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is specific energy in open channel flow?
A: Specific energy is the energy per unit weight of water measured with respect to the channel bottom. It represents the sum of depth and velocity head.

Q2: Why is critical depth important in channel design?
A: Critical depth helps determine whether flow is subcritical (tranquil) or supercritical (rapid), which affects wave propagation, energy dissipation, and structural design requirements.

Q3: How does critical depth relate to Froude number?
A: At critical depth, the Froude number equals 1. Froude number < 1 indicates subcritical flow, while > 1 indicates supercritical flow.

Q4: Can this formula be used for all channel shapes?
A: This specific formula (hc = 2/3 × Emin) applies to rectangular channels. For other channel shapes, the relationship between critical depth and minimum specific energy may differ.

Q5: What are practical applications of critical depth calculation?
A: Critical depth calculations are used in designing weirs, flumes, spillways, and other hydraulic structures, as well as in analyzing flow transitions and energy dissipation requirements.