Process intensification: Granular rheology.

Powders are fundamental in nature and almost every industry, being a final product e.g. pharmaceutics, foods, or an intermediate e.g. catalysts, fuels. Transitioning towards a net-zero economy and a sustainable industry requires designing better, more robust and efficient gas-solid contact devices that reduce the production of waste and the consumption of energy (e.g. reactors, dryers, absorbers). Powders however are rather complex materials, difficult t model. The interactions between individual particles originate an intricate collective behaviour that allows them to restructure in response to the action of an force and exhibit unique properties. When consolidated, a powder behaves as an elastic solid but when it is sufficiently dilute, it moves as a fluid. In a powder, the response to a force does not always depend only on its local properties, but it also on its structure around it, dictated by the arrangement of individual particles. The way particles organise and transmit stress is intimately related to their concentration, their surface properties and the cohesive forces at play. This fascinating dynamic determines how powders break, flow or agglomerate within any flow on their own or suspended in a stream of gas or a liquid. The same physics can lead to drastically different behaviours (e.g. formation of snowflakes in a storm, the flow of an avalanche, a sand storm or the deformation of dry or wet sand in the beach, the motion of magma or a concentrated solid suspension such as slurry or a cream). In this project, you will study the rheology of a cohesive powder using existing multi-scale models based in computational fluid dynamics (CFD) and the discrete element method (DEM) as well as experimental facilities. We will investigate the flow in different laboratory devices and characterisation chambers (e.g. https://pure.hw.ac.uk/ws/portalfiles/portal/41371195/1_s2.0_S00325910203...), and we will study the effect of cohesive forces (e.g. van der Waals, liquid bridges, electrostatics) in the powder structure and flow behaviour. The results of the computational work will be validated with theoretical models and experimental data obtained in an FT4 rheometer (e.g. https://aiche.onlinelibrary.wiley.com/doi/full/10.1002/aic.16945). Depending on your progress, this information can be used to develop more advance rheological models of cohesive mixtures, either based on traditional approaches or through the use of AI.

Other Comments: 

Student requirements:
- A quality-oriented mentality, good mathematics and affinity with computers.
- Genuine interest in modelling multiphase flows.
- IMPORTANT: Expertise with Linux & programming experience (e.g. C++, OpenFOAM, CFD) or an ability to quickly develop it.

Supervisor name: 
Dr Victor Francia
Supervisor and Deputy email addresses: 
v.francia@hw.ac.uk