Fluids Section
Supervised by Dr Ali Mashayek

Prior to starting her PhD, Lois completed an undergraduate and masters degree in Mathematics at the University of Cambridge. She joined the Centre for Doctoral Training in Mathematics of Planet Earth in September 2018. 

Why did you decide to study for a PhD at Imperial and join the Department of Civil and Environmental Engineering?
After graduating from my masters degree in 2016, I spent 2 years away from academia. The time out was valuable, and helped me to decide that a PhD was the right direction for my career. It was an easy decision to apply to the Centre for Doctoral Training in Mathematics of Planet Earth at Imperial! The programme really appealed to me as students are given a lot of freedom to choose projects from any Imperial department, and the cohort aspect of the CDT is very beneficial. I was also keen to make connections with the Grantham Institute, which I am now aligned with through the Science and Solutions for a Changing Planet DTP.

After a research masters year including taught courses in the Maths department and a short research project, I moved to the fluids section in the Civil and Environmental Engineering department where my group is based. This move has allowed me to keep important ties to the maths department while working in the multidisciplinary CEE department, which is directly relevant to my research interests. The fluids group has been very welcoming, and despite not having worked in the fluids lab for a while due to the pandemic, I still enjoy keeping in touch with my group and others through group meetings and in my role as section rep.

Tell us about your PhD project
My research is focused on the interaction of oceanic flows with sea floor topography. Mixing across density surfaces in the deep ocean (diapycnal mixing) helps to drive the global meridional overturning circulation, and has important implications for oceanic heat and tracer transport. A primary source of this deep ocean mixing is topographically induced turbulence, generated when tidal or geostrophic flows in the ocean interact with submarine ridges and seamounts.

Such interactions effectively transfer energy from large scales to smaller scales at which mixing and dissipation can act. These scales are unresolvable in global climate models, although the processes have been shown to have significant impact on the large scale circulation. We are interested in quantifying the characteristics and spatial and temporal distribution of this mixing to obtain a better physical understanding and create better parametrisation of sub-gridscale dynamics in global climate models.

I use a combination of high resolution realistic simulations and theory to understand some of these processes and their impact on the large scale flow. In particular, I focus on the role of large internal waves called lee waves that are generated when oceanic currents flow over underwater topography.

What impact do you hope you research will have/what do you hope your research will lead on to?
The overarching goal of physically understanding such processes is to be able to parametrise them in large scale models. Global climate models are far from the necessary resolution to capture such processes, and as such the impact of these processes on the resolved flow needs to be prescribed. Good climate models are needed for making predictions about the future of our oceans and atmosphere, and so understanding these small scale processes now and under changing climatic conditions is an important goal for oceanographers.

Does your research involve working with collaborators outside of the Department? If so who and why?
Being able to work with a range of collaborators is one of my favourite parts of this PhD. Within Imperial, we hold joint group meetings for geophysical fluid dynamics, allowing us to communicate our research across the Engineering, Maths and Physics departments. I was also a Geophysical Fluid Dynamics fellow at the Woods Hole Oceanographic Institution in the US in 2019, which allowed me to collaborate with scientists from other institutions.

What is a typical week like for you?
My typical week might include a mix of data analysis of numerical simulations, theoretical work, writing up completed work, helping give tutorials to undergraduates, attending group meetings and seminars, and meetings with my advisor and collaborators. I enjoy having lots of time to focus, which is one of the positives that has come out of home working.

How have your skills developed, both professional and personal?
In terms of technical skills, I have learnt a lot throughout the last couple of years about computing and data analysis, having come from a theoretical background. I’m trying to keep learning new skills through online courses regularly. On a personal level, I think I have improved at making research decisions and guiding my own work - as is the aim of a PhD.

What do you enjoy most about being a PhD student in the Department?
I enjoy having the freedom to study what I find interesting, and working some great people.