Wave Transmission Calculator
Use direct, coefficient, or empirical barrier mode.
Example Data Table
These screening examples use the empirical mode and the same built-in equations.
| Scenario | Hi (m) | Rc (m) | Bc (m) | d (m) | T (s) | Cp | Kt | Ht (m) | Loss (%) |
|---|---|---|---|---|---|---|---|---|---|
| Harbour crest wall | 1.20 | 0.80 | 4.00 | 3.50 | 5.50 | 0.82 | 0.3680 | 0.442 | 86.46 |
| Low crested berm | 1.50 | 0.35 | 6.00 | 4.20 | 6.20 | 0.88 | 0.5922 | 0.888 | 64.93 |
| Rock breakwater | 2.10 | 1.10 | 8.00 | 5.00 | 7.00 | 0.78 | 0.3877 | 0.814 | 84.97 |
| Submerged reef sill | 1.80 | -0.20 | 5.50 | 4.50 | 6.80 | 0.70 | 0.6867 | 1.236 | 52.84 |
| Sheet pile wave screen | 0.90 | 0.55 | 2.50 | 2.80 | 4.50 | 0.92 | 0.4442 | 0.400 | 80.26 |
Formula Used
1) Direct transmission coefficient
Kt = Ht / Hi
2) Transmitted wave height from a known coefficient
Ht = Kt × Hi
3) Empirical barrier screening estimate
Kt = clamp(Cp × e-Rc/Hi × e-Bc/L, 0.05, 0.95)
This screening relation reduces transmission as freeboard and crest width increase. It is useful for early construction planning and option comparison.
4) Wave energy transmission ratio
Energy ratio = Kt2
5) Wavelength from the dispersion relation
L = L0 tanh(2πd / L), where L0 = gT2 / 2π.
The file solves this iteratively to estimate the local wavelength used in the empirical barrier mode.
How to Use This Calculator
- Choose the calculation mode that matches your available data.
- Enter the incident wave height in metres.
- For direct mode, enter the measured transmitted height.
- For coefficient mode, enter a known or assumed Kt.
- For empirical mode, enter freeboard, crest width, water depth, period, and permeability factor.
- Press Calculate Transmission to show the result above the form.
- Review the coefficient, transmitted height, loss percentage, and chart.
- Use the CSV or PDF buttons to export the current result.
FAQs
1) What does the transmission coefficient mean?
It shows how much wave height passes through or over a barrier. A value of 0.30 means the transmitted height is 30% of the incident height.
2) When should I use direct mode?
Use direct mode when you already know both the incident and transmitted wave heights from monitoring, testing, or a previous study.
3) When is coefficient mode useful?
Coefficient mode is useful during quick scenario checks. If you have an assumed Kt from guidance or past projects, it instantly estimates transmitted height.
4) What does negative freeboard represent?
Negative freeboard means the crest is below the still water level. Submerged barriers usually transmit more wave energy than emerged barriers.
5) Why does crest width matter?
A wider crest increases the distance over which waves lose energy. In the screening equation, larger crest width reduces the predicted transmission coefficient.
6) Is this enough for final design?
No. This tool supports concept design, comparison, and early feasibility checks. Final construction decisions should include site data, safety factors, and specialist hydraulic review.
7) What permeability factor should I enter?
Use a lower value for denser, less permeable barriers and a higher value for more open structures. Keep your chosen factor consistent across option comparisons.
8) Why is wavelength calculated here?
The empirical mode uses wavelength to reflect depth and period effects. Longer waves interact with barrier width differently than shorter waves.