Novel multi-phase transport processes using yield stress fluids

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Visco-plastic fluids (with a yield stress) occur widely in industry & nature, e.g. toothpaste, wet pasta, cement and mud slurries, hair gel, paint suspensions. Fluids with yield stress may remain stationary even under an applied shear stress. As examples, consider a paint layer on a wall, fresh icing on a cupcake, yoghurt trapped in processing machinery or drilling fluid stuck in a wellbore during cementing. Although sometimes having a negative effect, the yield stress may also be exploited in novel ways leading to new flows. The first part of this project aims to develop 2 such new flow applications. The second part of the project concerns how to compute suspensions held in yield stress fluids in more efficient ways.***The first new application concerns droplet encapsulation and transport (on a large scale). The second new application concerns efficient transport of viscous fluids along pipelines. Both applications rely on a technique developed at UBC for eliminating interfacial instabilities (i.e. waves and eventual mixing) by using a yield stress fluid at the interface between fluids (VPL flows). Target applications for these flows would likely be within the oil & gas industry, although possibilities exist in slurry pipelining and food processing. The first project would improve wellbore integrity in enhancing delivery of downhole chemicals in e.g. acid fracturing of carbonate reservoirs. The second project is targeted at transport of heavy oil over long distances using reduced power. ***Regarding the second part of the project, applications of non-Newtonian suspension flows are very widespread in Canada's resource and energy industries, e.g. hole-cleaning (oil wells), mined tailings transport and deposition, dense pulp fiber flows, some viscous proppant transport. Key understanding, models and particularly computational tools are however missing and this project aims to correct this. Recent advances lead us to believe that this is possible. The impact of this would be mostly methodological, allowing others to tackle previously unreachable problems. ***The project also provides training for 2 PhD students and 1 postdoc, whom we hope will enter the Canadian workforce with their new skills. **