1. What is the Average Height of Roughness Protrusions?

The Average Height of Roughness Protrusions (Ra) is the arithmetic average of the absolute values of the roughness profile ordinates. It quantifies the surface roughness in fluid flow channels, which affects flow resistance and velocity distribution.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Ra \) — Roughness Value (m)
• \( RH \) — Hydraulic Radius of Channel (m)
• \( V_{avg(Tur)} \) — Average Velocity of Turbulent flow (m/s)
• \( V_{shear} \) — Shear Velocity (m/s)

Explanation: This formula relates the average height of roughness protrusions to the hydraulic radius and velocity parameters in turbulent flow conditions.

3. Importance of Roughness Calculation

Details: Accurate roughness calculation is crucial for predicting flow resistance, estimating energy losses, and designing efficient fluid transport systems in various engineering applications.

4. Using the Calculator

Tips: Enter hydraulic radius in meters, average velocity in m/s, and shear velocity in m/s. All values must be positive and valid for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is hydraulic radius?
A: Hydraulic radius is the ratio of the cross-sectional area of flow to the wetted perimeter of the channel.

Q2: What is shear velocity?
A: Shear velocity, also called friction velocity, is a velocity scale that characterizes shear stress at the boundary.

Q3: When is this formula applicable?
A: This formula is specifically designed for turbulent flow conditions in rough channels.

Q4: What are typical roughness values?
A: Roughness values vary significantly depending on the material, from very smooth surfaces (Ra ≈ 0.001 mm) to very rough surfaces (Ra > 1 mm).

Q5: How does roughness affect flow?
A: Increased surface roughness generally increases flow resistance and reduces flow efficiency due to higher energy dissipation.