Fetch Parameter In SMB Prediction Method Calculator

Fetch Parameter Formula:

\[ \phi = \frac{[g] \times Fl}{U^2} \]

Fetch Parameter (φ):

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1. What is the Fetch Parameter?

The Fetch Parameter is often associated with the concept of fetch, which is the unobstructed distance over which the wind blows across a body of water in a constant direction. It is a key parameter in wave prediction models.

2. How Does the Calculator Work?

The calculator uses the Fetch Parameter formula:

\[ \phi = \frac{[g] \times Fl}{U^2} \]

Where:

\( \phi \) — Fetch Parameter
\( [g] \) — Gravitational acceleration on Earth (9.80665 m/s²)
\( Fl \) — Fetch Length (meters)
\( U \) — Wind Speed (meters per second)

Explanation: This formula calculates the dimensionless fetch parameter used in wave prediction models to characterize the relationship between wind conditions and wave development.

3. Importance of Fetch Parameter Calculation

Details: Accurate fetch parameter calculation is crucial for predicting wave characteristics, coastal engineering design, maritime operations, and understanding wave generation processes in oceanography.

4. Using the Calculator

Tips: Enter fetch length in meters and wind speed in meters per second. Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is fetch length in wave prediction?
A: Fetch length is the unobstructed distance over which wind blows across water surface in a constant direction, directly influencing wave development.

Q2: Why is gravitational acceleration included in the formula?
A: Gravitational acceleration is included to make the fetch parameter dimensionless and to account for gravitational effects on wave formation.

Q3: What are typical values for fetch parameter?
A: Fetch parameter values vary widely depending on wind speed and fetch length, typically ranging from very small values for short fetches to large values for extensive fetches with strong winds.

Q4: How does fetch parameter relate to wave height?
A: The fetch parameter is used in empirical relationships to predict significant wave height, wave period, and other wave characteristics in the SMB prediction method.

Q5: Are there limitations to this parameter?
A: The fetch parameter assumes constant wind direction and speed over the fetch area, and may not account for complex wind fields or varying bathymetry.