Frictional flow patterns shaped by viscous and capillary forces (FriicFlow)

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Flow and mixing of fluids and granular materials occur in a wide range of processes. In nature, methane venting from ocean sediments represents a significant source of greenhouse gas, and the emission rate is intimately linked with complex interactions between the sediment and the rising methane gas in the form of bubbles or channels. Another example is the migration of gas through volcanic magma - a mixture of solid crystals and liquid melt - where the specifics of the complex flow patterning of the gas transport is thought to influence volcanic eruption behaviour. In the engineering sector, handling of granular suspensions and deformable porous materials are key in a wide range of industries from oil and gas, to food processing and pharmaceuticals. Despite the abundance and importance of such processes, fundamental knowledge of the physics that control them is lacking in many areas. These systems are inherently difficult to predict and control because of the very complex interactions taking place between the granular materials, liquids and gases during flow.The main aim of the project is to uncover the physics of two unknown mechanisms, namely the role of fluid viscosity and grain-fluid interactions in controlling the flow behaviour of frictional fluids and deformable materials. Using both experiments and computer simulations, we will explore the full range of viscosity ratio; high viscosity fluids injected into low viscosity host fluids and vice versa, where the host fluid contains granular materials of a range of concentrations, shapes and sizes. Where the two fluids meet, the meniscus will push or pull on the grains depending on the wetting properties, e.g. whether the grains are hydrophilic ("water-loving") or hydrophobic ("water-hating"). Through finely controlled experiments matched with theory and simulations we will reveal the effect of wetting on the flow behaviour. The new insight will be incorporated into models that will allow a much more accurate prediction of frictional flow behaviour, and ultimately to improving forecasting of natural events such as volcanic eruptions, and to optimize industrial processing of granular suspensions and deformable materials.