Deterministic reconstruction and reproduction of multi-directional irregular waves based on linear summation model

Abstract

Accurately reproducing multi-directional irregular waves in laboratory or numerical wave basin is crucial for in-depth study of real wave-action on marine structures. In this paper, the EEED (Equal-Energy-in-Each-Division) and PTPD (Phase-Time-Path-Difference) approaches are described, and their capability for reconstructing multi-directional irregular waves is assessed. The key difference between these two methods is the determination of the component wave directions. Theoretically and (arbitrary) numerically simulated multi-directional waves with different directional distribution width and wave steepness are reconstructed, and the latter waves are further reproduced in a numerical wave basin. The consistency between the reconstructed and the theoretical/measured waves demonstrates the approaches are acceptable. Furthermore, the variation of the quantitative error between the reconstructed and the theoretical/measured waves in the spatial domain (rr/Ls) is analyzed. This variation increases with the size of rr/Ls, but the errors are acceptable as long as this size is reasonable. The application ranges are evaluated based on a qualitative comparative analysis between the reconstructed waves and the theoretical/measured ones and the quantitative reconstruction error along rr/Ls. The PTPD approach is generally better than EEED method. The optimum relative separation for wave gauges using the PTPD approach should be smaller than 0.12Ls.