Energy Dissipation Rate By Battjes And Janssen Calculator

Battjes and Janssen Formula:

\[ \delta = 0.25 \times \rho_{water} \times [g] \times Q_B \times f_m \times (H_{max}^2) \]

Water Density:

kg/m³

Percentage of Waves Breaking:

Mean Wave Frequency:

Maximum Wave Height:

Energy Dissipation Rate per unit Surface Area:

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1. What is the Battjes and Janssen Formula?

The Battjes and Janssen formula calculates the energy dissipation rate per unit surface area for breaking waves. It provides an estimation of the amount of energy lost by viscous forces in wave breaking processes, which is crucial for understanding coastal dynamics and sediment transport.

2. How Does the Calculator Work?

The calculator uses the Battjes and Janssen formula:

\[ \delta = 0.25 \times \rho_{water} \times [g] \times Q_B \times f_m \times (H_{max}^2) \]

Where:

\( \delta \) — Energy dissipation rate per unit surface area (W/m²)
\( \rho_{water} \) — Water density (kg/m³)
\( [g] \) — Gravitational acceleration (9.80665 m/s²)
\( Q_B \) — Percentage of waves breaking (%)
\( f_m \) — Mean wave frequency (Hz)
\( H_{max} \) — Maximum wave height (m)

Explanation: The formula accounts for the physical properties of water, gravitational effects, wave breaking characteristics, and wave dimensions to estimate energy dissipation.

3. Importance of Energy Dissipation Rate Calculation

Details: Accurate energy dissipation rate estimation is crucial for coastal engineering, sediment transport studies, wave energy conversion systems, and understanding coastal erosion processes.

4. Using the Calculator

Tips: Enter water density in kg/m³, percentage of waves breaking in %, mean wave frequency in Hz, and maximum wave height in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for water density?
A: Fresh water density is approximately 1000 kg/m³, while sea water density ranges from 1020-1030 kg/m³ depending on salinity and temperature.

Q2: How is the percentage of waves breaking determined?
A: This is typically estimated through field observations or calculated based on wave height to water depth ratios and wave steepness parameters.

Q3: What are typical values for mean wave frequency?
A: Ocean waves typically have frequencies between 0.05-0.3 Hz, corresponding to periods of 3-20 seconds.

Q4: What factors influence maximum wave height?
A: Wind speed, duration, fetch length, water depth, and local bathymetry are the primary factors affecting maximum wave height.

Q5: Are there limitations to this formula?
A: The formula assumes uniform wave conditions and may be less accurate for complex wave fields or in shallow water environments with significant bottom friction effects.