ESCO 2020 talk: The role of granular mechanics and porous flow for ice sheet behavior

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ESCO 2020, the 7th European Seminar on Computing, was held between June 8 and 12. I presented my current research on ice-sheet and sediment mechanics. Full abstract:

The role of granular mechanics and porous flow for ice sheet behavior in a changing climate

Ice sheets and glaciers commonly flow over sedimentary deposits, in particular in areas of fast ice flow. The basal sediments are weakened by high water pressure provided by ice melt and limited drainage. Areas of fast flow are primary contributors to sea-level rise, so an accurate understanding of the thermomechanical multiphysics problem of ice, water, and sediment is crucial for predicting dynamical behavior under future climate scenarios. The in-situ observational basis from borehole measurements shows that the subglacial environment is highly dynamic. Water pressures, strain rate, and glacial sliding patterns are extremely variable in time and space, and hint towards significant complexity beyond current modelling approaches. Sediment transport by ice flow reshapes the bed, and can feed back to the ice flow physics. In this presentation I explain our efforts to numerically describe the subglacial sediment mechanics and fluid dynamics, and how the processes affect ice sheet behavior. GPU-based particle-scale simulations using the discrete element method and porous fluid dynamics provide detailed insight into sediment and meltwater dynamics. However, the intense computational requirements severely limit their applicability to coupled simulations of ice and bed. Our newest efforts use continuum models of non-local granular fluidity to simulate essential behavior on larger spatial and temporal scales. We show that the variability observed in field borehole measurements can be explained by considering the coupled dynamics of the ice-water-sediment system. From these dynamics ice flow has the ability to rapidly reshape its bed, providing additional feedbacks to ice contribution to sea level in a changing climate.

Slides and video below: