Periodic Reporting for period 4 - HIGHWAVE (Breaking of highly energetic waves)
Okres sprawozdawczy: 2023-03-01 do 2024-08-31
HIGHWAVE, which is a project co-hosted by University College Dublin, Ireland, and Ecole Normale Supérieure Paris-Saclay, France, is an interdisciplinary project at the frontiers of coastal/ocean engineering, earth system science, statistics and fluid mechanics that explores fundamental open questions in wave breaking. Why do waves break, how do they dissipate energy and why is this important? Forecasts of breaking wave conditions are important to all who live, work or travel on or near sea and ocean, and the economic impact is significant for end users, not only in harbour and maritime traffic control (logistics and safety), but also in offshore oil and gas, wave and wind energy (operations and maintenance), and coastal monitoring. Wave breaking is a topic of considerable relevance in terms of transfers between the atmosphere and oceans. Taking breaking waves into account in the design and operation of marine structures will become an important part of adaptation to climate change. Societal benefit is clear: improving marine safety conditions for ocean workers, reduced loss of life, public access to better wave forecasts for recreational activities, enhanced environmental protection.
HIGHWAVE research program is structured in four workpackages:
Work Package 1 (WP1) is directed towards energy dissipation through wave breaking. The main objective of WP1 is to develop an innovative approach that includes accurate wave breaking physics into coupled sea state and ocean weather forecasting models.
Work Package 2 (WP2) is taking to the laboratory natural overtopping observations from the field. The main objective of WP2 is to obtain improved criteria for the design of ships and coastal/offshore infrastructure subject to extreme breaking wave loads and/or overtopping.
Work Package 3 (WP3) focuses on the effect of wave breaking in the nearshore zone. The main objective of WP3 is to quantify the effect of highly energetic breaking waves on the sea floor in the nearshore, even at depths of several dozen metres.
Work Package 4 (WP4) addresses all the engineering issues raised by work packages 1, 2 and 3. The main objective of WP4 is to develop new concepts in wave measurement with improved characterization of wave breaking using real-time instrumentation and machine learning tools.
HIGHWAVE research program is structured in four workpackages:
Work Package 1 (WP1) is directed towards energy dissipation through wave breaking. The main objective of WP1 is to develop an innovative approach that includes accurate wave breaking physics into coupled sea state and ocean weather forecasting models.
Work Package 2 (WP2) is taking to the laboratory natural overtopping observations from the field. The main objective of WP2 is to obtain improved criteria for the design of ships and coastal/offshore infrastructure subject to extreme breaking wave loads and/or overtopping.
Work Package 3 (WP3) focuses on the effect of wave breaking in the nearshore zone. The main objective of WP3 is to quantify the effect of highly energetic breaking waves on the sea floor in the nearshore, even at depths of several dozen metres.
Work Package 4 (WP4) addresses all the engineering issues raised by work packages 1, 2 and 3. The main objective of WP4 is to develop new concepts in wave measurement with improved characterization of wave breaking using real-time instrumentation and machine learning tools.
During the first 30 months of the project, which started only 6 months before the COVID-19 pandemic struck, we have developed greatly improved understanding of breaking waves in both laboratory and numerical experiments. We have developed advanced theoretical and numerical models for realistic wave breaking.
The key development of WP1 (New description of wave breaking onset and dissipation) is a new mathematical wave model including unbroken as well as broken waves. The model is fed by several ingredients: (i) a breaking onset threshold that is robust to the range of mechanisms that contribute to wave breaking: bathymetry, spectral bandwidth, directionality, wind forcing, currents and any combination of these; (ii) a breaking strength parameter linked to the breaking threshold parameter; (iii) a source term representing wind forcing. Numerical work has been completed or is in progress for the three ingredients.
The bulk part of the work in WP2 (Loading due to wave breaking) is to obtain improved criteria for the design of ships and coastal/offshore infrastructure subject to extreme breaking wave loads and/or overtopping. Laboratory experiments using a smart boulder have been performed to describe loads by breaking waves and discover a generic threshold parameter for loading severity. The experimental results have been partially analysed.
The bulk part of the work in WP3 (Underwater transport of large size loose particles and irreversible morphological impacts) is to quantify the effect of highly energetic breaking waves on the seabed, even at depths of several dozen metres. Field experiments have been prepared to discover which parameters influence breaking wave erosion and to discover a threshold parameter for quasi-irreversible beach motion.
WP4 (Wave breaking measurement) has concentrated most of the work performed so far. The research station that will allow wave measurement including full spatial information (amplitude and direction) of a given sea state in real time has been built. The algorithms to clean the raw data and to provide the real-time data at 1-minute intervals from the raw data have been partly developed. A tool named Wave Obs was set up to provide a daily forecast collection of various ocean and meteorological parameters for the benefit of the local community or any other interested parties. This tool turned out to be an interesting standalone project involving state of the art statistics.
The key development of WP1 (New description of wave breaking onset and dissipation) is a new mathematical wave model including unbroken as well as broken waves. The model is fed by several ingredients: (i) a breaking onset threshold that is robust to the range of mechanisms that contribute to wave breaking: bathymetry, spectral bandwidth, directionality, wind forcing, currents and any combination of these; (ii) a breaking strength parameter linked to the breaking threshold parameter; (iii) a source term representing wind forcing. Numerical work has been completed or is in progress for the three ingredients.
The bulk part of the work in WP2 (Loading due to wave breaking) is to obtain improved criteria for the design of ships and coastal/offshore infrastructure subject to extreme breaking wave loads and/or overtopping. Laboratory experiments using a smart boulder have been performed to describe loads by breaking waves and discover a generic threshold parameter for loading severity. The experimental results have been partially analysed.
The bulk part of the work in WP3 (Underwater transport of large size loose particles and irreversible morphological impacts) is to quantify the effect of highly energetic breaking waves on the seabed, even at depths of several dozen metres. Field experiments have been prepared to discover which parameters influence breaking wave erosion and to discover a threshold parameter for quasi-irreversible beach motion.
WP4 (Wave breaking measurement) has concentrated most of the work performed so far. The research station that will allow wave measurement including full spatial information (amplitude and direction) of a given sea state in real time has been built. The algorithms to clean the raw data and to provide the real-time data at 1-minute intervals from the raw data have been partly developed. A tool named Wave Obs was set up to provide a daily forecast collection of various ocean and meteorological parameters for the benefit of the local community or any other interested parties. This tool turned out to be an interesting standalone project involving state of the art statistics.
In addition to the scientific progress beyond the state of the art on wave breaking, the project has been of tremendous benefit to non-academic audiences. A large part of our research in the HIGHWAVE project involves fieldwork and relies fundamentally on the support of the communities on the Aran Islands and in Connemara for its success. Before the official start of the project, the residents of Inis Mór, Inis Meáin, and Inis Oír had a chance to see the plans and voice their opinions at public meetings, one on each of the three islands. Following these meetings, the project’s measurement campaign started on Inis Meáin, where the community was very receptive. The local community is now part of HIGHWAVE and the goal at the end of the project is to transform the HIGHWAVE research station into an international research station on Inis Meáin. From the purely scientific point of view, the main goal of HIGHWAVE is to provide a more complete understanding of wave breaking, such as providing an accurate description of wave breaking in operational wave models and revolutionizing field measurements of breaking waves. Using combinations of Dynamical Systems theory, Machine Learning, Computational Fluid Dynamics and novel measurement techniques is a highly innovative interdisciplinary approach promising new insights into wave breaking. However, in trying to compare the predictions of our models with existing ocean wave measurements, it has become clear that we need to develop a new approach to measuring breaking waves using a variety of sensors (wave buoys, radar, stereo vision) such that transient extreme wave events can be reliably captured even when they occur rarely. During the second half of HIGHWAVE, an ERC Proof of Concept proposal in collaboration with marine industry will be submitted to develop a new approach to ocean wave measurements including low-cost real-time transmission of data and fast data processing.