Currently we have no funded postdoctoral or postgraduate positions available. However, there are competitively awarded scholarships available from the university for postgraduate research degrees (e.g. PhD projects). If you are interested in working on one of the projects below, or have an idea that is related to one the areas detailed in this website, email me your latest academic transcript and CV (pdf format please) so that I can access what your chances of getting a scholarship are.
Linking structure to mechanics: Modelling cell deformation under flow
Cells within the blood have widely varying mechanical properties, not only dependent on the cell type, but also on the age and health of the cell. To illustrate, the mechanical properties of red blood cells (RBCs or erythrocytes) are dominated by their area-conserving viscous phospholipid membrane, and to a lesser extent, by their internal elastic spectrin cytoskeleton that is tethered to this membrane. In a healthy RBC the properties of the RBC's cytoplasm (roughly Newtonian, with a viscosity approximately 5 times that of the surrounding plasma) are relatively unimportant in determining the cell's mechanical behaviour. However, in diseased states such as sickle cell anemia, diabetes mellitus and malignant malaria, RBCs show greatly reduced deformation, implying that viscoelastic cytoplasm and cytoskeleton properties become more important. Leukocytes (White Blood Cells or WBCs) are also surrounded by a viscous membrane, but in these cells the cytosketal network is stronger than RBCs, resulting in a cell that deforms less and (in general) more elastically. Like RBCs, in diseased states the physical properties of WBCs change. For example, neutrophils in patients with sepsis, septic shock and adult respiratory distress deform less due to increased actin (cytoskeleton) polymerisation. To be useful in a diagnosis or design setting, cell models for predicting cell deformation and flow behaviour need to be able to link cell structure to cell mechanics, and to be able to cope with a wide spectrum of cell materials.
Within this PhD project we will develop a cell model based on the viscoelastic Navier-Stokes equations, capable of resolving the viscoelastic behaviour of the cytoplasm, combined with a diffuse interface method for modelling both the elastic strains (extensional for areal expansion and shear) and viscous shear stress within a membrane interface. Having this model we will be able to: a) model all blood cell types using a single consistent approach, allowing cell deformation and flow to be predicted as a function of material structure; and b) probe, via shape analysis and flow behaviour, how disease affects the underlying mechanical properties of each cell type, not limiting ourselves to (healthy) cells that are either dominated entirely by membrane or cytoplasmic forces.
This is an ambitious project, but one that could also be very rewarding and help to directly save lives. It would involve programming new numerical methods, while concurrently understanding (and advancing) knowledge of cell structure and mechanics. We have a number of collaborators that are awaiting the results of this research!
Predicting vapour layer collapse under Leidenfrost droplets
Film boiling impacts occur when a volatile liquid approaches a high temperature solid (see Dynamic Leidenfrost). These types of solid/liquid interactions occur in numerous applications, including solid fuel fire extinguishment, fuel/combustion chamber interactions in internal combustion engines and various types of industrial cooling.
Despite much experimental and theoretical research, models that are able to predict when vapour layer collapse occurs have not been developed. Water, for example, typically nucleate boils at temperatures up to at least 400°C, whereas simulations predict that film boiling impacts occur at 240°C and above. It is important to be able to predict what boiling regime will occur for any given application as the two boiling regimes have vastly different heat transfer (and corresponding evaporation) rates.
This PhD proposal involves using CFD and analytical techniques to study this problem.
Another idea. We have a number of collaborators working with the closely related droplet coalescence problem.
Modelling functionalised wettability
A liquid wetting a solid is a universal process occurring in a wide variety of natural, industrial and domestic systems. Recent studies are finding that in nature, organisms use specific surface structures to control wetting, to the advantage of the organism. Current international research is focused on reproducing this functionalised wettability by mimicking these naturally occurring surface structures.
What hampers our ability to expand upon this bio-mimicry and design new surfaces tailored to meet the needs of real world applications is an inadequate understanding of the relationship between surface morphology and wettability. For example, models are available to predict limiting contact angles when a droplet either completely wets a solid (Wenzel state), or rests only on the top surfaces of a structured surface (Cassie state), however we have no ability to a-priori predict which model will be relevant for a particular surface design.
Hence, the purpose of this project is to develop and apply novel CFD (Computational Fluid Dynamics) techniques to simulate the behaviour of a liquid as it wets a structured surface. A unique feature of the approach will be that fundamental surface energy concepts will be directly applied in the numerical modelling - hence, this is an interdisciplinary project that will involve aspects of both Fluid Dynamics and Physical Chemistry. Experimental results generated using a variety of structured surfaces are available for validation and comparison.