The theoretically maximum power absorbed from ocean waves by a system of several interacting oscillating bodies and water columns is studied for the case of unrestricted oscillation, as well as for the case when certain restrictions are applicable for the oscillation amplitudes. For the case when the radlation-damping matrix is singular, it is shown that the unconstrained maximum absorbed power is unambiguous even if the optimum oscillation is not then unique. Two different kinds of constraints are investigated for an axisymmetical system of an OWC in a floating body.
Maximising the power absorbed from ocean waves by a system of several interacting oscillating bodies was studied during the late 1970s by Budal[1], Evans[2] and Falnes[3]. A particularly simple proof of the optimum condition, for the case of unrestricted amplitudes, was presented by Evans, when it was assumed that the radiation-resistance matrix is non-singular, i.e. invertible. If amplitude constraints are applicable, numerical analysis has to be used except in certain simple problems which may be studied analytically. One such ~mple was presented in 1981 by Evans[4] when one common global constraint was applied to all body amplitudes. Also in this analysis a non-singular radiation-resistance matrix was assumed. In the present paper this analysis and the above-mentioned simple proof is generaiised to the case where the radiation-resistance matrix is singular. Moreover, the derivation is also generaiised to a situation where the radiation-resistance matrix, which is symmetric and real, is replaced by a hermitian complex radiationdamping matrix. The motivation for the latter generaiisation is the following. It appears that if the system of oscillating bodies is extended to include also a group of oscillating pressure distributions (or oscillating water columns (OWCs) with pneumatic power takeoff), then the system's radiation-damping matrix is complex and hermitian.
