Validation of a numerical wave tank based on overset mesh for the wavestar-like wave energy converter in the South China Sea

Abstract

The CFD-based numerical wave tanks (CNWTs) have become a valuable numerical tool for research and development (R＆D) of wave energy converters (WECs) with improvements in computational efficiency. Verification and validation are crucial during the development of a CNWT to demonstrate the precision of the numerical results. The CNWT was utilized to conduct model tests on a designed point-absorber wavestar-like WEC at a scale of 1:17.5. A model of the wavestar was tested at the physical wave tank (PWT) at the Tianjin Research Institute. Verification and validation investigations were carried out on the variation wave strategies of the CNWT, which involved test cases with varying wave encounter angles (WEAs), wave steepnesses (WSTs), and wave periods. The results indicate that the amplitude of the float motion response increased with the growth of the WEA, and the motion response of the model under WEA of 180 deg is 17.3 % larger than the 0 deg. The phenomenon of cut jet flow and gas-liquid mixing that occurred in both PWT and CNWT for sea states with larger WST. The detailed error and deviation analyses and frequency domain study of numerical and experimental results were conducted. The experimental measurements indicate that the numerical results for the motion displacement of the WEC and the free-surface elevation surrounding the WEC are in satisfactory agreement.