We are always looking for good PhD students to join our group, however you need to be awarded a university supported scholarship, and these scholarships are quite competitive. For some specific projects (see below) we have some top-up stipends available. 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 ONLY please) so that I can assess what your chances of getting a scholarship are. Note that I receive many such email requests, and depending on my teaching and research schedule, it may take me several weeks for me to process your email. You can find more information on UniMelb graduate research scholarships here. As part of the application process you will need to do a brief literature review within the area of interest, and write a 600 word project proposal.
Sticky cells: Understanding and modeling platelet flow and binding in blood
Platelet function is central to maintaining a healthy vascular system. Similar to other types of cells, platelets respond to a variety of stimuli from their local environment: the concentration of chemical agonists, bonds with neighbouring species, fluid dynamic stresses, and even their history. On a single cell level, many of these biophysical processes are not understood or quantified. At the blood vessel level, we do not have the multiscale modelling techniques that translate this single cell knowledge to capture how collections of platelets behave. Using a combined experimental and numerical development program we will address these deficiencies and develop a model that predicts how blood flows through vascular scale geometries.
Studying how biochemical species and platelets interact in blood will advance our understanding of the basic biological processes underpinning normal haemostasis, ultimately leading to better therapies for conditions underlying cardiovascular disease, the leading cause of death in Australia. The developed modelling techniques will allow a new class of strongly interacting multiphase fluid dynamics problems to be solved, with broad application within the health, minerals and energy sectors.
This is a large and exciting collaborative project being conducted by a team of researchers from UniMelb, RMIT (Australian Centre for Blood Diseases) and CSL. Within this large project we are targeting a number of specific PhD areas, including blood rheology during coagulation, blood biochemistry, vWF dynamics and platelet binding (to name a few). Some projects are simulation based, others experimental and some a combination. As with the other PhD projects suggested on this page, you would need to gain a scholarship to commence one of these PhD projects, however PhD top-up stipends are available.
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! A top-up stipend is available.
Predicting droplet coalescence
When two droplets collide in a liquid phase, the thin film of fluid that exists between them must drain before they can coalesce. Depending on parameters such as their relative impact velocity, size, and fluid properties such as species, surface charge and presence of surfactants/contaminants, the droplets may coalesce quickly, slowly, or not at all.
As a component of a larger project that aims to develop a better understanding of how organic drops behave in a water phase, we have developed a CFD model of droplet coalescence that captures thin film drainage (see Thin Film Rupture). This specific PhD topic aims to further develop and apply this model to industrially relevant systems, in order to optimise the performance and efficiency of various solvent extraction technologies
This PhD project sits within a larger ARC funded project on simulating processing equipment. There are top-up stipends available. We also have experimentally based PhD positions available in the same area.
Predicting vapour layer collapse under Leidenfrost droplets
Film boiling impacts occur when a volatile liquid approaches a high temperature solid (see Thin Film Rupture). 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.
This project is closely related to the coalescence problem outlined above.
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.