Presets
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Wave and device
Wave amplitude is the elevation in metres, the period in seconds. The column is a mass on a hydrostatic spring pushed by the wave and braked by damping and by the air pressure above it. The vent throat sets how easily the air escapes, which tunes the response.
Model checks
The science
What is modelled
A single-degree-of-freedom water column of length 2.55 m and area 2.35 m2 with a compressible air pocket above it. The air leaves through a vent whose flow follows an orifice law, the turbine takes power from the air flow, and the wave forcing is a deep-water sine with a small second harmonic.
Equations
- Column:
M dv/dt = K (a hw - z) - B v - A p, withK = rho g A,M = rho A L. - Air pocket:
dp/dt = (gamma p0 / V)(A v - Q). - Vent:
Q = sign(p) Cd Av sqrt(2 |p| / rhoair). - Power:
Pel = eta |p Q|. - Waves:
k = omega2 / g(deep water).
Checks run in the page
- Wave dispersion and wavelength.
- Orifice flow law and its sign.
- A flat sea produces nothing.
- Electric energy against efficiency times the integral of air power.
- The column follows the wave period.
Honest simplifications
A reduced-order model, not CFD: linear hydrostatic stiffness, a single added-mass length, a fixed absorption factor, a regularised turbine torque and a simple end stop. Real OWC performance needs wave-tank or CFD data.
What to try
- Sweep the wave period and compare with the power curve: output peaks near the resonance of the column.
- Shrink the vent area: the chamber pressure grows and the turbine power changes.
- Press Storm and watch the end stop limit the heave while the power spikes.