Frictional fluid dynamics of granular flows; uniting experiments, simulation and theory

Fluid-driven granular processes are commonplace throughout the industrial and natural worlds. A large share of global energy consumption relates to the processing of grains and particulate matter in construction, agriculture, the pharmaceutical industry, and the food and energy sectors. Meanwhile, erosion in rivers and underneath glaciers, as well as natural hazards such as landslip and sinkhole formation, are exacerbated by changing precipitation patterns and the melting of land ice caused by climate change. As we strive to achieve net zero, it is vital that we develop a comprehensive understanding of the physics of granular flow, both to reduce our carbon footprint and to better manage rapid changes in our geophysical environment.

Grain flows driven by fluid remain poorly understood. The fluid's influence on the grains, the friction between the granular material, and the properties of the grains themselves all result in highly complex behaviour. The FFDflow fellowship will carry out extensive laboratory experiments to observe fluid-driven flows across a wide range of conditions to reveal their underlying physics, taking into consideration all of these aspects. These flows will also be explored using theoretical models and computer simulation forming part of a collaborative benchmark study to validate a variety of models for use in fluid-driven granular flows.

The FFDflow fellowship will also study how fluid-driven flows can occur in the till underneath glaciers. This is a particularly pressing matter as the acceleration of marine-terminating ice streams (corridors of fast flowing ice) is a source of huge uncertainty regarding sea-level rise, and the dynamics of ice streams is largely controlled by processes occurring at and around the interface between ice and the bed. A series of experiments will be performed using a laboratory setup designed to explore the environment underneath a glacier, with the aim of obtaining a better understanding of the way in which grain flow arises in these settings and how it might impact the ice above.