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

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.

Our goal is to uncover the physics that controls mixing and flow of fluids and granular materials. Such multiphase flows are important in a range of industries that handle granular suspensions, pastes and particulates. However, the complex flow interactions are in many cases poorly understood, leading to inefficiencies and low predictability. Our results will contribute to a solid scientific foundation for applied R&D in geotechnical and process engineering which will help practitioners innovate and optimise new technologies in the future. The project is "blue sky", targeting the basic physics of the subject matter, and the industrial and economic impact of our work is therefore projected to occur in the mid- to long term.

The focus of our impact strategy in the short term will be on achieving societal impact through outreach and engagement with people outside science. Outreach and engagement is critical to building trust between scientists and the public, and to nurture confidence in unbiased, factual science. It is a worrying trend that people's mistrust in science is increasing, despite science becoming ever more intertwined with the big political issues of the day. The outreach component is centred around The Swansea Science Festival, and the Oriel Science Gallery. Both the festival and the gallery attract thousands of visitors every year, from a broad demographic representing a cross-section of society in and around the Swansea area in South Wales. Audience surveys confirm the impact of the events, with e.g. 96% of adult visitor at the Swansea Science Festival rating it 4 or 5 out of 5, and 92% of under 16s choosing a "happy face" to describe the festival. Similarly, 95% of visitors to Oriel Science's "pop-up gallery" felt that they had learnt more about science from the exhibition. Both the festival, through its Family Weekend, and Oriel Science seeks to inspire young people in particular, thereby stoking interest and curiosity about science from an early age. 74% of under 16 visitors to the Swansea Science Festival said they would like to study a STEM subject. A dedicated website will mirror the content of the exhibitions and allow us to reach an audience beyond the South Wales region. We will further make use of opportunities to submit results of general interest to established outreach channels (e.g. FYFD, EPSRC Science Photo competition etc.), and post on social media such as YouTube and Twitter.

The training and professional development of the early career postdocs are a major contribution to the STEM economy. The technical and soft skills that they will acquire are highly sought after in both industry and academia. We further aim to include undergraduate students in the project by means of their final year research project. We believe this a win-win strategy: the project gains by more "hands on deck" and a lively group, and the students benefit by having the extra motivation of working towards a larger goal as a team. Some of the projects will be dove-tailed with the outreach activities, providing the extra inspiration of potentially having your work contributing to a public showcase event. Swansea University will provide match funding for the consumable required for these projects, as well as a limited number of paid summer internships contributing to the running of the Oriel Science showcase. We believe participation in these activities will provide invaluable experience and inspiration to the students involved.