Geometric Effects on Maximum Power Absorption Efficiency for a Single, Two-Dimensional Heaving Body

Abstract

Numerical simulations are carried out to study the effects of body geometry on maximum power absorption efficiency. Diffraction theory is used to study two-dimensional, single, surface-piercing, heaving bodies impinged by regular, harmonic, linear waves. The complex amplitude of the excitation force in the heave direction is calculated numerically using AQWA. Additionally, a wave flume experiment is proposed to measure the complex amplitude of the excitation force in the heave direction, in order to study the maximum power absorption efficiency. From the complex amplitude of the excitation force (Xi), the radiated wave amplitudes at positive infinity (α+) and negative infinity (α-) are calculated using: Xi = 2pAagCgi---------------w The maximum power absorption efficiency for a given frequency is then calculated using: ^ = |a+|2---------|a+|2+|a_|2 The radiated wave amplitude at positive infinity is calculated from the amplitude of the excitation force as a wave impinges the curved face of the body. Rotating the body 180° and measuring the amplitude of the excitation force yields the radiated wave amplitude at negative infinity. Results indicate concave bodies experience the greatest excitation force and convex bodies yield the higher maximum power absorption efficiency, under the condition that the wavelength is relatively short and the draft and waterline cross-sectional area remain constant. For long waves, the geometric effect becomes insignificant.