Quantifying energy dissipation in wind-forced breaking waves.

Wave breaking at the ocean surface is a ubiquitous process across the global oceans and seas. It represents a key physical process that affects the evolution of the surface wave field and the interaction between the overlying atmosphere and the underlying ocean. Breaking waves limit the height of individual waves, generate extreme surface flows, and when sufficiently steep can lead to the occurrence of slamming on structures in the marine environment. Accurate descriptions of wave breaking occurrence, shape and energy dissipation are needed to better inform design standards for offshore structures such as renewable energy devices, ocean-going vessels and platforms.
In oceanographic terms, breaking waves are a significant source of turbulence to the ocean boundary layer where they enhance mixing in the upper ocean. When they are sufficiently energetic they entrain air to form surface whitecaps and sub-surface bubble clouds that enhance air-sea transfer of poorly soluble gases such as carbon dioxide, and generate tiny aerosol particles that help to form clouds. Wave breaking is a fundamental process relevant to engineering, oceanography and atmospheric science.

Due to practical constraints, the majority of laboratory investigations of breaking waves typically do not examine the direct effects of wind forcing. This project, however, will use state-of-the art wave-making and wind-generating facilities in the hydrodynamics laboratory at the Department of Civil and Environmental Engineering at Imperial College London, to examine the relationship between breaking wave energy dissipation, air entrainment and whitecap foam evolution of wind-forced breaking waves. This approach will provide a more realistic setting in which to study individual breaking waves, and help to de-convolve the roles played by non-linear wave dynamics and direct wind shear stress on the breaking process and subsequent two-phase flow evolution. Data will be collected with (i) digital cameras to measure the extent of air entrainment, bubble size distributions, and foam evolution, (ii) wave gauges to record the surface water elevation and (iii) underwater hydrophones to record the acoustic signatures of wave breaking.

As a Ph.D. student, you will be responsible for performing the laboratory experiments, data collection and data analysis. Access to images of oceanic breaking waves in the ocean will also provide opportunity to compare laboratory results to oceanic wave breaking. You will receive training in aspects related to performing and designing experimental laboratory work, data collection methods and analysis techniques, image processing techniques and processing of acoustical data. A strong motivation to carry out high quality experimental work, develop innovative data analysis techniques and to follow your own curiosity is highly desirable. You will also have the opportunity to attend relevant engineering and oceanography conferences, where you can present your research to, and network with, other researchers.

Academic Requirements:
Candidates should have at least an upper second class undergraduate degree in Engineering, Physics, Maths, or other numerate field. An M.Sc. in any of these areas or in oceanography/marine science is also desirable.

How to Apply:
Interested candidates should send a CV, a cover letter, a transcript of academic track records and the name of two potential referees to Dr. Adrian Callaghan ([Email Address Removed])