Multiphase Frictional Fluid Flows

Displacement dynamics in settling granular mixtures, in which inter-particle friction has a central role, have received little attention. Such 'frictional fluids' are ubiquitous in nature and engineering. For example, they have a key role in landslides, where fluidization causes the rheology to jump rapidly from solid- to fluid-like behaviour. Of interest in engineering applications is the role of frictional granular mixtures in oil and gas recovery, and potentially for processes linked to CO2 geo-sequestration. From a materials science point of view, frictional fluids are strongly related to other complex fluids. Frictional fluids reflects jamming mechanisms on the molecular level that resemble static friction on the macro-level. We have studied these both by simulation and experiments and found a rich variety of patterns. These patterns have a wide range of different characteristics that allow us to determine under which conditions they were formed. Recently a geological realization of the typical labyrinthine patterns have been discovered in an israeli desert.

Pattern formation occurs in a wide range of systems representing virtually every discipline of science. By characterizing new pattern forming systems, we come closer to an elusive goal of non-equilibrium physics: to understand the underlying principles go verning self-organized phenomena, and why so many seemingly unrelated processes produce such remarkably similar outcomes. We have discovered a new pattern formation system by introducing Coloumb friction to the ordinary fluid dynamics of viscous, pressu re and capillary forces. Recent results indicate that there is a myriad of never before observed pattern formation dynamics on display, and that the system undergoes a series of phase transitions resulting in different characteristic morphologies. We pro pose to pursue these findings using a complementary approach involving precise experiments, numerical simulations and theoretical modeling. Our aim is to uncover new knowledge regarding how the interactions between the individual particles (friction, coll isions, cohesion) lead to complex large scale dynamics (pattern formation, jamming, intermittency), how our observations relate to other pattern forming systems, and to characterize the dynamic behavior of materials ubiquitous in industrial processing and the environment. National and international collaboration forms an integral part of the proposal. The project will benefit from, and strengthen, research networks within Norway, and an emerging collaboration between Norway and Australia.