wave_energy: Calculate the wave energy flux

Description

Calculates the wave energy flux (power per meter of wave crest) given either (1) the significant wave height and peak period or (2) the wind speed at 10m, fetch length and (optionally) water depth.

Usage

wave_energy(height = NA, period = NA, wind = NA, fetch = NA, depth = NA)

Value

Wave energy flux, in kW/m.

Arguments

height: Significant wave height, in meters.
period: Peak wave period, in seconds.
wind: Wind speed at 10m, in m/s.
fetch: Fetch length, in meters.
depth: Water depth, in meters.

Details

Given the significant height (H) and peak period (T), the wave energy flux is calculated as: $$\frac{\rho g^2}{64 \pi} H^2 T$$, where $\rho$ is the density of water (998 kg/m^3) and g is the acceleration of gravity (9.81 m/s^2).

If both height and period are missing, they are estimated from on the wind speed at 10m ($U_{10}$) and the fetch length (F) as described in Resio et al. (2003): $${U_f}^2 = 0.001 (1.1 + 0.035 U_{10}) {U_{10}}^2$$ (friction velocity) $$\frac{g H}{{U_f}^2} = \min (0.0413 \sqrt{\frac{g F}{{U_f}^2}}, 211.5)$$ $$\frac{g T}{U_f} = \min (0.651 (\frac{g F}{{U_f}^2})^{1/3}, 239.8)$$ If the depth (d) is specified, it imposes a limit on the peak period: $$T_{max} = 9.78 \sqrt{\frac{d}{g}}$$ (in seconds)

References

Resio, D.T., Bratos, S.M., and Thompson, E.F. (2003). Meteorology and Wave Climate, Chapter II-2. Coastal Engineering Manual. US Army Corps of Engineers, Washington DC, 72pp.

Examples

Run this code

 # With height and period arguments
 wave_energy(8, 1)

 # With wind, fetch and depth arguments (must be named)
 wave_energy(wind = 12, fetch = 15000, depth = 10)

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