Description:

Nucleate boiling occurs when a solid surface is heated above an adjacent 
liquid’s 
saturation temperature. In this scenario, vapour forms at preferential 
nucleation 
sites on the heated surface. While there has been much research into the 
computational modelling of nucleate boiling [1, 2], there have been 
comparatively 
fewer studies into the boiling of liquid metals, especially in the presence of 
magnetic fields. This is despite the relevance to nuclear fusion blanket design. 

Fusion blankets are multi-purpose chambers that surround plasma in a tokamak 
reactor. A critical role of the blanket is to transfer nuclear heat (arising 
from 
high-kinetic energy bombarding neutrons) away from the first wall and into a 
steam 
generator where the steam is subsequently used to drive a turbine in a standard 
thermodynamic steam cycle. 

In the context of fusion, a Lithium-Lead eutectic is often used as a working 
fluid. This metal flows in the presence of strong magnetic fields, inducing 
electric currents. Magnetohydrodynamic (MHD) body forces act on the fluid (the 
Lorentz force). This MHD effect opposes the motion of the metal and lowers the 
flow rate for a given pump head; typically, flow rates are too low to transfer 
sufficient heat from the first-wall to prevent thermal damage.

A proposed solution to this is to allow the coolant to boil. The advantage of 
this 
is twofold: 1) nucleate boiling is a highly effective method of heat transfer 
due 
to the high latent heat of vaporisation of typical working fluids. 2) In the 
vapour phase, the Lorentz force is much less severe. This allows for greater 
flow 
rates (and therefore enhanced heat transfer) for the same pressure drop along a 
given duct length.

This PhD will focus on developing the necessary computational fluid dynamics 
(CFD) 
tools to effectively model bubble nucleation in metals subject to strong 
magnetic 
fields. Such a tool does not currently exist, and the study of such flows is 
currently predominantly undertaken experimentally (with limited insights and 
high 
cost due to the fact metals are not transparent to visible wavelengths of 
light). 
The magnetic field alters bubble nucleation dynamics (bubble shape, departure 
diameter and frequency, nucleation site density, etc.). Once developed and 
validated against existing experimental data in the literature [3], the tool 
will 
be used to perform fundamental flow physics studies in both pool and flow 
boiling 
configurations to better understand the complex flow physics involved. 

In this project, you will join a team of researchers active in MHD [4], heat 
transfer and nucleate boiling modelling [1,2], leveraging the combined knowledge 
of the group. You will have opportunities to collaborate with researchers at 
UKAEA.

References 

[1] G. Giustini and R. I. Issa, A method for simulating interfacial mass 
transfer 
on arbitrary meshes, Physics of Fluids 2021 Vol. 33 Issue 8, DOI: 
10.1063/5.0058987
[2] G. Giustini, H. Kim, R. I. Issa and M. J. Bluck, Modelling Microlayer 
Formation in Boiling Sodium, Fluids 2020 Vol. 5 Issue 4, DOI: 
10.3390/fluids5040213
[3] Takahashi, M., Inoue, A., Aritomi, M. and Matsuzaki, M., 1995. Studies on 
magnetohydrodynamic flow characteristics and heat transfer of liquid metal two-
phase flow cooling systems for a magnetically confined fusion reactor. Fusion 
engineering and design, 27, pp.663-677.
[4] De Rosis, A. and Skillen, A., 2022. Vortex dynamics in an electrically 
conductive fluid during a dipole–wall collision in the presence of a magnetic 
field. 
Physics of Fluids, 34(8).



Funding: 

At Manchester we offer a range of scholarships, studentships and awards at 
university, faculty and department level, to support both UK and overseas 
postgraduate researchers applying for competition and self-funded projects. 

For more information, visit our funding page or search our funding database for 
specific scholarships, studentships and awards you may be eligible for.

This project is also eligible for the Osborne Reynolds top-up Scholarship which 
provides an additional £1500 per year top-up to other funding sources for 
outstanding candidates. Successful applicants will be automatically considered 
for 
this top-up.