## Our Research

We conduct research and offer research training in fluid mechanics, convection and heat transfer. Our current activities include rotating and non-rotating horizontal convection informing global currents in Earth's oceans, process industries and microprocessor cooling, and magnetohydrodynamic (MHD) flow and heat transfer in electrically conducting fluids within ducts for heat extraction from future fusion reactors.

We specialize in the use of high-order numerical schemes (spectral element method and spectral methods) to obtain complex thermo-fluid flow solutions, and in advanced analysis techniques yielding insights into the stability, modes of transition, and energy exchanges in these flows. Our work is conducted in collaboration with leading international laboratories.

## Natural convection

Density gradients in a fluid (whether caused by differences in temperature, salinity, etc.) invoke motions due to buoyancy imbalances known as natural convection. We are interested in a class of natural convection flows driven by uneven buoyancy supply across a horizontal boundary, known as horizontal convection. A major motivator for research into horizontal convection is its idealization of buoyancy supply as a driver for global-scale ocean currents, where solar radiation leads to significantly different surface temperatures between the colder polar regions and warmer tropical regions. More broadly, horizontal convection finds application across process industries (e.g. glass melts, etc.), passive ventilation of building interiors, and at smaller scales the cooling of high-performance microprocessor architecture. We are currently investigating the properties of horizontal convection under rotation, transient features during the inception of horizontal convection, scalings between heat transport and the strength of thermal forcing in these flows, and the special case of horizontal convection in enclosures very much longer than they are deep.

## Magnetohydrodynamics

When an electrically conducting fluid passes through a magnetic field, a force known as the Lorentz force acts on and modifies the flow. These induced motions in turn generate induced currents and magnetic fields that may substantially modify the flow. We are particularly interested in MHD flows within ducts and their associated heat transfer. When exposed to a very strong transverse magnetic field, these flows organise in the direction of the field, adopting a quasi-two-dimensional state. We exploit this phenomenon to execute fast and accurate simulations of these flows under a modified two-dimensional framework. More broadly we are investigating the properties of the three-dimensional counterpart to these flows using the quasi-static MHD approximation and our in-house high-resolution spectral element-Fourier 3D algorithm: our interest is in the mechanisms inciting the destabilisation of the duct boundary layers, and demonstrating the existence of a quasi-two-dimensional path to turbulence.

## Rotating flows

Rotating flows are ubiquitous: we observe them directly as water empties from a basin down a drain, or when stirring a coffee. Rotating flows are a major component of atmospheric dynamics (cyclones, etc.) and ocean flows. When an inner mass of fluid rotates at a different rate to surrounding fluid, shear layers develop at the interface that exhibit fascinating instability behaviour. Such shear layer instabilities are readily observed from satellite imagery of Earth's and other planetary atmospheres: a particularly striking example being the hexagonal feature at Saturn's north pole. We use a specialised linear stability analysis algorithm supported by three-dimensional direct numerical simulation to elucidate the behaviour of these rotating flows.