Green water evolution on a fixed structure induced by incoming wave trains

Abstract

Marine structures, such as ships and oil platforms, are often subject to green water propagating over their decks and causing overloading. Understanding the spatial and temporal evolution of these events allows estimation of water loads and thus an analysis of the structural dynamics. From this information the design of marine structures can be improved. This article investigates the evolution of green water events on a fixed structure, produced by incoming wave trains in a wave flume. Wave trains were generated with different wavelengths and heights. High-speed video was employed to capture details of the green water flow and image-based methods were used to extract water elevation data for the spatial and temporal analysis. A preliminary evaluation of an engineering convolution approach for capturing the water-on-deck elevations generated by the wave trains is also included. The experimental results were systematically carried out to allow the study of the effect of the wave trains on freeboard exceedance, the distribution of water on the deck, and the green water evolution. The convolution approach reproduced adequately the water elevations in time and space for all the study cases. It also captured the trends of amplitudes and approximated the time at which the peak values occurred, showing potential for further green water analysis.

Keywords:

• Green water evolution
• convolution model
• virtual wave probe (VWP)
• regular waves
• water elevation
• image processing

Acknowledgments

The first author thanks the UNAM-DGAPA postdoctoral fellowship for support provided. Special thanks are given to Enrique Hernández from II-UNAM for his help in performing the experiments and to Jill Taylor for her help in the revision of the manuscript.

Disclosure statement

Authors declare no competing financial interests or personal relationships that could have appeared to influence the study presented in this paper.