Some design aspects of an absorbing 3D wavemaker

A new absorbing multidirectional wavemaker is under development at the Danish Hydraulic Institute. In this process numerous aspects of the design and control of multielement wavemakers as well as the theory for wave generation and active absorption have been considered. This paper focuses on two specific and specialized points. First, the influence of finite segment width on the wave field generated is analysed for different types of paddle front. In this connection a new criterion for the truncation of directional spectra to be generated is suggested. Second, the appearance and reduction of aliasing problems for 3D active absorption is discussed. Aliasing appears due to the spatial sampling typically used for obtaining a hydrodynamic feedback in the absorption procedure.