Journal of Fluid Mechanics

Wave generation by an oscillating surface-pressure and its application in wave-energy extraction

A. J. N. A.  Sarmento a1 and A. F. de O.  Falcão a1
a1 Mechanical Engineering Department, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1096 Lisboa Codex, Portugal

Article author query
sarmento aj   [Google Scholar] 
falcão af de o   [Google Scholar] 


A two-dimensional analysis, based on linear surface-wave theory, is developed for an oscillating-water-column wave-energy device in water of arbitrary constant depth. The immersed part of the structure is assumed of shallow draught except for a submerged vertical reflecting wall. Both the cases of linear and nonlinear power take-off are considered. The results show that air compressibility can be important in practice, and its effects may in general be satisfactorily represented by linearization. The analysis indicates that using a turbine whose characteristic exhibits a phase difference between pressure and flow rate may be a method of strongly reducing the chamber length and turbine size with little change in the capability of energy extraction from regular waves. It was found in two examples of devices with strongly nonlinear power take-off that the maximum efficiency is only marginally inferior to what can be achieved in the linear case.

(Published Online April 20 2006)
(Received March 2 1982)
(Revised August 24 1984)