Numerical Modelling of Wave Energy Absorbers
This work is a continuation of a previous DTI project on "The Numerical Prediction of the Performance of a Solo Duck". Results of the previous study are extended by computing the reactive powers required to attain the optimal complex control. Results are also presented for the optimal real control for cases in which power is absorbed in one degree of freedom. This corresponds to a pure damping control force, i.e. with no reactive power. The equations for optimal power absorption under an amplitude constraint have been reformulated to permit non-absorbing (i.e. uncontrolled) degrees of freedom. The effect of releasing a degree of freedom is investigated. The properties of heaving and surging devices are studied by considering a 20 metre diameter hemisphere. Power absorption through inclined degrees of freedom is also considered. The effect of device geometry is investigated by simple volume-conserving transformations of the hemisphere. Results are presented for the solo duck considered in the previous project in all possible configurations of a) surge, heave and pitch system, and b) fore, aft and pitch system. Results are also presented for three widths of a rounded solo duck. Cooperative research with the European Commission JOULE programme is described.