Host: University College Dublin

SUPERVISION: Professor Frédéric Dias & Doctor Vikram Pakrashi

Summary: PhD Thesis focusing on local structural impact due to wave breaking

HIGHWAVE covers simultaneously past, present and future energetic ocean waves. The project research, associated with sustainable environmental science and technology, will help future generations to improve environmental practice. HIGHWAVE is a cutting-edge mathematical project that uses real-time raw data harvested in situ by the project team to develop new models and new algorithms. These new models will provide information about air and water exchange in oceanic environments, boulder deposits, erosion and structural damage.

The PhD student will be based in the School of Mathematical Sciences of University College Dublin. The wave group (5 PhD students, 3 postdocs, 1 lecturer, 1 engineer) has an international reputation in the study of waves and computational fluid mechanics.

The work packages (WPs) of the project are summarized below:

The present PhD deals with WP2. The work will be performed by a PhD student and a postdoc working closely together.
The focus of WP2 is on local structural impact due to wave breaking. The range of impact scales is O(1 m) to O(10 m). Laboratory experiments will be performed to find the parameter (e.g., normalized energy flux) that determines the severity of loading due to overtopping or breaking waves impacting on a structure. For the case of boulders, the threshold of initiation of motion will be found. In August 2017, a set of 128 experiments involving 18 boulders were performed at Queen’s University Belfast. It was not always the case that larger waves moved larger boulders. No clear relationship between displaced mass and any of the obvious parameters such as the maximum wave height, cliff-top fluid velocity, maximum water thickness on the cliff was found.
The bulk part of the work in WP2 will be to obtain improved criteria for the design of ships and coastal/offshore infrastructure subject to extreme breaking wave loads and/or overtopping.

This objective will be met by two key results:

• Description of any load possibly induced by a breaking wave and/or overtopping  in terms of elementary loading processes
• Discovery of ageneric threshold parameter (e.g., normalized energy flux) for loading severity
• The key goals, together with the proposed methodology, include:
  • Development of an accurate depth-resolving two-phase model that accounts for the complex horizontal/vertical motions and mixing that occur during overtopping (CFD tools will be used)
  • Development of a dual experimental and numerical benchmark to analyse loads induced by breaking waves and overtopping
  • Searchofaparameter(e.g.,normalizedenergyflux)thatdeterminestheseverityof loads induced by breaking waves impacting on a structure and overtopping (Machine Learning regression methods will be used)
  • Field investigation of loads induced by breaking waves (pressure sensors and low- cost subsea camera systems will be installed in several natural and man-made coastal structures)

The expected duration of the PhD is 4 years.

To find out more please visit UCD website