Interaction of Wavemaker Motion with False Bottom for Practical Aspects of Wave Basin Operation

Abstract

Multi-domain eigenfunction expansion method is utilized to analyze the interaction of wavemaker motion with false bottom for operational aspects of wave basin. A flap type wavemaker is considered while the water depth for a floating structure or a vessel is adjusted with the help of false bottom. This study aims to reveal the wave generation capability of this wavemaking system. The hydrodynamic analysis requires appropriate consideration of wavemaker, false bottom, basin bottom, and the downstream wall, respectively. The wave motion on water due to an oscillating wavemaker is described under the assumption of ideal fluid flow. The free surface boundary is linearized while the entire domain is decomposed into multiple rectangular zones. For each zone, the corresponding eigenfunction expansion is applied so that matching conditions may be satisfied on each boundary thereupon. Convergence and accuracy of the method of solution is demonstrated for a number of submergence depths of false bottom and wave periods. Energy balance is confirmed and the detailed characteristics of the underlying phenomenon is given including reflection and transmission.

Keywords: wavemaker motion, false bottom, wave basin, multi-domain eigenfunction expansion, wavemaking performance, wave reflection, wave transmission