1. What is Perimeter of Trapezoidal Channel Section?

Definition: The perimeter of a trapezoidal channel section is the total length of the wetted surface (bottom and sides) in contact with the water.

Purpose: It's crucial for calculating hydraulic radius, which is important in determining flow characteristics in open channels.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P \) — Perimeter of channel (meters)
• \( B \) — Bed width of channel (meters)
• \( y \) — Depth of canal (meters)
• \( \theta \) — Side slope angle (radians)

Explanation: The formula accounts for both the bottom width and the two sloped sides of the trapezoidal channel.

3. Importance of Perimeter Calculation

Details: Accurate perimeter calculation is essential for determining hydraulic radius, which affects flow velocity, discharge calculations, and channel design efficiency.

4. Using the Calculator

Tips: Enter the bed width, depth, side slope in radians, and tolerance percentage (default ±5%). All values except tolerance must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is side slope input in radians?
A: The trigonometric cotangent function in the formula requires the angle in radians for accurate calculation.

Q2: What's a typical side slope for trapezoidal channels?
A: Common slopes range from 0.5 to 1.5 radians (about 30° to 60°), depending on soil stability and design requirements.

Q3: What does the tolerance percentage represent?
A: It shows the acceptable range (±%) around the calculated perimeter, accounting for construction variations.

Q4: How does perimeter affect channel design?
A: Larger perimeter increases friction loss but may provide more stable side slopes, affecting both efficiency and safety.

Q5: Can I use degrees instead of radians?
A: Convert degrees to radians first (radians = degrees × π/180) as the calculator requires radians input.

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