Fluid structure interaction of violent wave events

A study into the influence of structure properties on breaking wave impacts

Master thesis (2024)

Authors

F.J. Scholte Mechanical Engineering

Contributors

P.R. Wellens Ship Hydromechanics and Structures - Mechanical, Maritime and Materials Engineering (mentor)
A.D. Boon Ship Hydromechanics - Mechanical, Maritime and Materials Engineering (graduation committee member)
H.J. de Koning Gans Ship Hydromechanics and Structures - Mechanical, Maritime and Materials Engineering (graduation committee member)
Faculty
Mechanical Engineering
More Info
expand_more

Published Date

02-10-2024

Language

English

Reuse Rights

Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.

Faculty

Mechanical Engineering

Abstract

This study investigates the effect of dynamic properties of a structure on the magnitude of impacts loads of breaking waves. A literature review in the field of violent wave impact on flexible structures is done. From this review, it is concluded that the hydro flexibility of structures have great impact on the fluid-structure interaction. In earlier studies, it is found that models of constructions in breaking waves are not accurate yet, using knowledge that is available up until now. There are studies that show suggestions of influence on the structures own properties. However, no extensive research had been done in this field. That is why the main objective of this study is to research if the natural frequency of a construction is of influence on the impact force of violent waves.

To answer the research question, a model is made and an experiment is carried out. The model consists of two parts, first a pendulum is used to represent a simplified structure to interact with a breaking wave. Using the model, a simulation of pendulums with different natural frequencies is done. The pendulums interact with the same wave each time. The second part of the model consists of a beam that is impacted by a breaking wave. Simulations are carried out where beams with different natural frequencies are impacted by the same wave.

To verify the model and further elaborate on the research question, an experiment is done. This experiment is done in the Sloshing rig at the faculty of Mechanical Engineering at the TU Delft. During the experiment, four different plates with different natural frequencies are used. They are exposed to the same wave impact each time. The model and the experiment results are compared and used to form a conclusion.

It is concluded that wave impacts are of higher magnitude on structures with a higher natural frequency. The difference between the measured and predicted forces indicates that the fluid- structure interaction of these plates lead to this difference. This can be explained by the different fluid- structure interaction for plates with different natural frequencies. If velocities of the plates with higher natural frequencies are higher, the Morison component of the impact force becomes larger. Therefore these impacts can become higher than for other structures. As the natural frequency of the plate increases, the results show relatively higher measured deflections as well.