Community Research and Development Information Service - CORDIS

The performance of a solo duck

The motion of a solo duck wave energy absorber has been investigated using 3-dimensional linear water wave diffraction theory. Numerical predictions of hydrodynamic coefficients were compared with analytical results for a hemisphere, and experimental results for a solo duck.

A 3-dimensional linear wave diffraction computer program can be used as a productive design tool for the linear regime. Singularities in the damping matrix gave rise to large excursions under complex conjugate control, even in short waves.

The control strategy is modified by the application of motion constraints. Even when the constraints are imposed, the duck is able to absorb power from outside the width of sea it occupies. A 10 m diameter, 29 m wide, solo duck has a relative capture width of a little over 2 for the centre of the South Uist wave spectrum in power levels of about 35 KW/metre.

The efficiency of the 6 degrees of freedom system is larger in short oblique waves than in short head on waves. This suggests that the performance of the duck may be improved by modifying its geometry.

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David PIZER
Tel.: +44-31-6505715
Record Number: 11039 / Last updated on: 1995-01-09
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