Experimental Research on Nonlinear Deflection Wave of the Floating Plate

Abstract In this research, the nonlinear wave beneath a 2D floating plate, representing a prototype Very Large Floating Structure (VLFS), is investigated. This special nonlinear phenomenon, arising from fluid-structure interaction, is referred to in this paper as the nonlinear deflection wave. First, the theoretical solution of the nonlinear deflection wave, which shares similarities with the conventional Stokes Wave Theory, is introduced. Based on the theoretical solution, the resonance period associated with the second-order response is identified, revealing significant differences compared to the conventional Stokes Wave Theory. To validate the theoretical solutions, a model test is designed and conducted in a two-dimensional water tank. A series of regular wave tests with varying wave periods is conducted, with the wave periods selected near the resonance period predicted by the theoretical solutions to more clearly generate the nonlinear deflection wave. The resonance period predicted by the theoretical solutions is successfully validated through the model test. Additionally, the phase-reversing behavior anticipated by the theoretical solutions is also observed during the model test. Finally, third-order deflection waves observed in the model tests are briefly introduced, along with a concise introduction to the third-order theoretical model. Based on the model test results, the existence of the nonlinear deflection wave phenomenon, attributed to fluid-structure interaction and predicted by theoretical derivation, is conclusively verified.