1. What is Wetted Perimeter?

Wetted Perimeter is defined as the surface of the channel bottom and sides in direct contact with the aqueous body. It is a crucial parameter in hydraulic engineering for calculating flow characteristics in open channels and pipes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P \) — Wetted Perimeter (m)
• \( A_{cs} \) — Cross Sectional Area of Flow (m²)
• \( r_H \) — Hydraulic Radius (m)

Explanation: The wetted perimeter is calculated by dividing the cross-sectional area of flow by the hydraulic radius, which represents the efficiency of the channel section in conveying water.

3. Importance of Wetted Perimeter Calculation

Details: Accurate calculation of wetted perimeter is essential for determining flow resistance, calculating discharge in open channels, designing efficient hydraulic structures, and analyzing sediment transport in rivers and canals.

4. Using the Calculator

Tips: Enter cross-sectional area in square meters (m²) and hydraulic radius in meters (m). Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between wetted perimeter and hydraulic radius?
A: Wetted perimeter is the total length of the channel boundary in contact with water, while hydraulic radius is the ratio of cross-sectional area to wetted perimeter, representing the efficiency of the flow section.

Q2: How does wetted perimeter affect flow characteristics?
A: A larger wetted perimeter increases friction between the water and channel boundaries, which reduces flow velocity and increases energy loss in the system.

Q3: Can this formula be used for both open channels and closed conduits?
A: Yes, the formula applies to both open channels and closed conduits running partially full, where the wetted perimeter can be clearly defined.

Q4: What are typical values for hydraulic radius in different channel types?
A: Hydraulic radius values vary widely depending on channel geometry. For wide rectangular channels, it approximates the flow depth, while for circular pipes running full, it equals D/4 where D is the pipe diameter.

Q5: How does channel shape affect the wetted perimeter?
A: Different channel shapes with the same cross-sectional area can have significantly different wetted perimeters. More efficient channel shapes minimize wetted perimeter for a given area, reducing flow resistance.