Ocean Mixing Parameterisation via Categorisation of Nonlinear Flow Structures - Project 2: Experimental Validation

One of the key challenges for large-scale climate models is to accurately parameterise the mixing which occurs in the oceans. Such mixing occurs at small-scales, well below the grid-resolution of the climate models, and consists of the turbulent exchange of heat and salt between neighbouring regions of fluid. In order to build a robust parameterisation of this mixing, we must take a data-driven approach in which oceanographic data are algorithmically categorised according to the type of dynamics they represent.

Mixing at small scales in the ocean is mediated by a class of flows called stratified shear flows. Within such flows, there are three potential routes, or instabilities, leading to turbulence, each with a distinct degree and vigorousness of mixing. Recently, Dr Tom Eaves proposed a categorisation scheme for oceanographic data taken at a single instant in time, which aims to distinguish between these three instabilities at linear and nonlinear levels (predicting what type of mixing will happen next, and what type of mixing just occurred, respectively).

This project will investigate the fidelity of the categorisation scheme, taking it beyond the simplified flows considered in Dr Eaves’ initial study, primarily through the completion of a carefully-controlled parametric experimental modelling study on stratified shear flows. We will use data from this study to determine the extent to which the linear and nonlinear categorisation algorithms agree with one another (i.e. to what extent predictions at one time about what is about to happen agree with predictions at some later time about what just occurred).

This project will make use of experimental flume facilities within the Environmental Fluid Mechanics laboratory at the University of Dundee, as well as specialist measurement equipment including micro-conductivity probes for high-resolution density profiling and particle image velocimetry/laser-induced fluorescence (PLIF) for turbulent flow field measurements generated by shear-induced mixing. This data will be used as direct validation of the computational methods utilised in Project 1 and to help inform the mathematics underlying the categorisation schemes to build and interrogate nonlinear flow structures associated with stratified shear flows.

Key skills developed through the project include the experimental modelling of turbulent fluid flows, mathematical high-Reynolds-number fluid dynamics, and the development/application of advanced techniques for the measurement of fluid flows.

For informal enquiries about the project, contact Dr Alan Cuthbertson (a.j.s.cuthbertson@dundee.ac.uk)

For general enquiries about the University of Dundee, contact doctoralacademy@dundee.ac.uk

Our research community thrives on the diversity of students and staff which helps to make the University of Dundee a UK university of choice for postgraduate research. We welcome applications from all talented individuals and are committed to widening access to those who have the ability and potential to benefit from higher education.

QUALIFICATIONS

Applicants must have obtained, or expect to obtain, a first or 2.1 UK honours degree, or equivalent for degrees obtained outside the UK in a relevant discipline.

English language requirement: IELTS (Academic) score must be at least 6.5 (with not less than 5.5 in each of the four components). Other, equivalent qualifications will be accepted. Full details of the University’s English language requirements are available online: http://www.dundee.ac.uk/guides/english-language-requirements.

APPLICATION PROCESS

Step 1: Email Dr Alan Cuthbertson (a.j.s.cuthbertson@dundee.ac.uk) to (1) send a copy of your CV and (2) discuss your potential application and any practicalities (e.g. suitable start date).

Step 2: After discussion with Dr Cuthbertson, formal applications can be made via our direct application system. When applying, please follow the instructions below:

Apply for the Doctor of Philosophy (PhD) degree in Civil Engineering: Civil engineering research degrees | University of Dundee.

Please select the study mode (full-time/part-time) and start date agreed with the lead supervisor.

In the Research Proposal section, please:

-       Enter the lead supervisor’s name in the ‘proposed supervisor’ box

-       Enter the project title listed at the top of this page in the ‘proposed project title’ box

In the ‘personal statement’ section, please outline your suitability for the project selected.