Rugosity Coefficient Given Drag Force Calculator

Rugosity Coefficient Formula:

\[ n = 1 - \frac{F_D}{\gamma_w \times (G - 1) \times t \times \sin(\alpha_i)} \]

Drag Force (F_D):

Unit Weight of Fluid (γ_w):

N/m³

Specific Gravity of Sediment (G):

Volume per Unit Area (t):

Angle of Inclination (α_i):

rad

Rugosity Coefficient (n):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Rugosity Coefficient?

The Rugosity Coefficient, also known as the Manning's n, quantifies surface roughness in channels, affecting flow velocity and resistance. It's a crucial parameter in hydraulic engineering for calculating flow characteristics in open channels.

2. How Does the Calculator Work?

The calculator uses the Rugosity Coefficient formula:

\[ n = 1 - \frac{F_D}{\gamma_w \times (G - 1) \times t \times \sin(\alpha_i)} \]

Where:

\( n \) — Rugosity Coefficient (Manning's n)
\( F_D \) — Drag Force (N)
\( \gamma_w \) — Unit Weight of Fluid (N/m³)
\( G \) — Specific Gravity of Sediment
\( t \) — Volume per Unit Area (m)
\( \alpha_i \) — Angle of Inclination of Plane to Horizontal (rad)

Explanation: The equation calculates the roughness coefficient based on drag force, fluid properties, sediment characteristics, and inclination angle.

3. Importance of Rugosity Coefficient Calculation

Details: Accurate rugosity coefficient calculation is essential for predicting flow resistance, designing hydraulic structures, and analyzing sediment transport in open channels and rivers.

4. Using the Calculator

Tips: Enter drag force in Newtons, unit weight of fluid in N/m³, specific gravity of sediment, volume per unit area in meters, and angle of inclination in radians. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of rugosity coefficient values?
A: Rugosity coefficient values typically range from 0.01 (smooth surfaces like glass) to 0.15 (rough natural channels with vegetation).

Q2: How does rugosity coefficient affect flow velocity?
A: Higher rugosity coefficients indicate rougher surfaces, which create more resistance to flow and result in lower flow velocities for the same hydraulic conditions.

Q3: What factors influence the rugosity coefficient?
A: Surface material, vegetation, channel irregularity, sediment size, and channel alignment all influence the rugosity coefficient value.

Q4: How is rugosity coefficient used in Manning's equation?
A: In Manning's equation (V = (1/n) × R²/³ × S¹/²), the rugosity coefficient (n) is in the denominator, directly affecting flow velocity calculations.

Q5: Can rugosity coefficient change over time?
A: Yes, rugosity coefficient can change due to sediment deposition, erosion, vegetation growth, or human modifications to the channel.