Study of the effect of breaking waves on different wave fields: tests carried out in the large ocean engineering tank at Centrale Nantes

The oceans are dynamic and unpredictable environments where waves play a key role in many natural and industrial phenomena.

Understanding their behaviour is essential, particularly for maritime safety and the development of renewable marine energy. It is in this context that Centrale Nantes' ocean engineering tank recently hosted an experimental test campaign as part of the WASANO international research partnership (I-SITE NExT project), the aim of which is to study the effect of breaking waves on different wave fields. Directional focused waves were generated initially and then realistic extreme sea states (multidirectional irregular waves) were studied.

48 wave probes were positioned carefully in the tank to measure free surface elevation and carry out various measurements:

• Recording wave characteristics at several points across the entire width of the tank; 
• Assessing the amount of energy dissipated by breaking waves between two positions in the tank
• Analysing the quality of wave generation and reconstruction from the measured data;
• Studying the effect of the directional spread of the irregular sea state on wave statistics.

The aim of these tests is to gain a better understanding of the highly complex physical phenomena of extreme conditions, so that they can be taken into account more effectively in the design of marine structures.

This data is invaluable for refining numerical models and gaining a better understanding of the mechanisms behind extreme waves. One of the key aspects is the comparison of experimental data with numerical simulations based on the HOS (High-Order Spectral) method. These simulations are used to reproduce the waves observed in the tank and to assess the accuracy of the models used.

The results of the WASANO campaign will help to improve wave modelling and optimise the design of maritime infrastructures and offshore energy systems. A better understanding of extreme waves will also enhance safety in the ocean environment, whether for ships, floating offshore wind turbines or any other marine structure.

Photos: Bertrand Malas