Granular and particle-laden flows: from laboratory experiments to field observations

Abstract

This review article provides an overview of dry granular flows and particle fluid mixtures, including experimental and numerical modeling at the laboratory scale, large scale hydrodynamics approaches and field observations. Over the past ten years, the theoretical and numerical approaches have made such significant progress that they are capable of providing qualitative and quantitative estimates of particle concentration and particle velocity profiles in steady and fully developed particulate flows. The next step which is currently developed is the extension of these approaches to unsteady and inhomogeneous flow configurations relevant to most of geophysical flows. We also emphasize that the up-scaling from laboratory experiments to large scale geophysical flows still poses some theoretical physical challenges. For example, the reduction of the dissipation that is responsible for the unexpected long run-out of large scale granular avalanches is not observed at the laboratory scale and its physical origin is still a matter of debate. However, we believe that the theoretical approaches have reached a mature state and that it is now reasonable to tackle complex particulate flows that incorporate more and more degrees of complexity of natural flows. environments, landslides initiate on continental margins or on oceanic ridges, are assumed to be more or less coherent solid masses, and may be more voluminous than their subaerial equivalents (Hampton et al. (1996), Masson et al. (2006)). While submarine landslide activity is rarely observed, recent high resolution surveys of underwater depth of ocean floors reveals small to large landslide deposits that shape the morphology of medio-oceanic ridges (Cannat et al. (2013)). In contrast, turbidity currents are generally smaller flows with low particle volume fraction (Normack et al. (1993), Meiburg and Kneller (2010), Cantero et al. (2012)). Snow avalanches can be dry or wet and the distinction is made between dense slab avalanches, of moderate thickness and high particle concentration, and powder snow avalanches of larger thickness and much lower particle concentration (Hopfinger (1983), Ancey (2001), Schweizer et al. (2003)). Volcanoes generate hot mixtures of volcanic gas and particles, called pyroclastic density currents, through lateral explosion of a magma body or the gravitational collapse of a lava dome or of an eruptive column (Druitt (1998), Branney and Kokelaar (2002), Roche et al. (2013a), Dufek (2016)). Pyroclastic flows and surges represent the dense and dilute end-members of mechanisms, respectively, and often coexist as a dense underflow is commonly overridden by a dilute turbulent ash cloud. Debris flows are dense mixtures of water and solid particles generated in various subaerial environments on Earth and on other planets (Iverson (1997), Iverson et al. (1997), Zanuttigh and Lamberti (2007), Mangold et al. (2010)) and they can derive from landslides (Scott et al. 2001). Lahars are debris flows resulting from the mixing of pyroclastic material with water ...

Characterization of wood‐laden flows in rivers

“…Since then, monitoring techniques and physical and numerical models have contributed greatly to our present knowledge of sediment transport (Kondolf et al, 2005;Gyr and Hoyer, 2006;Rickenmann, 2016Rickenmann, , 2017Tsutsumi and Laronne, 2017), but wood transport has received much less attention. We follow here the nomenclature of particle-laden flows (Delannay et al, 2017) to define woodladen flows (WLFs) as a class of two-or three-phase flow. [Colour figure can be viewed at wileyonlinelibrary.com] 1695 WOOD-LADEN FLOWS been rarely described.…”

Continuum viscoplastic simulation of a granular column collapse on large slopes: μ(I) rheology and lateral wall effects

“…5,6 As a result, the mechanical investigation of these flows based on a complete 3-D modelling and comparison with laboratory experiments is a relevant way to validate or improve the constitutive relations that are being used. In this context, the experimental and numerical study of the release of rectangular or cylindrical granular columns (so-called granular column collapse) on channelled or unconfined horizontal and inclined beds has become widely used to analyze the dynamics and deposit of gravity granular flows (see, e.g., the work of Delannay et al 11 for a review). The reason is that it has a typical and reproducible transient behavior.…”

A Free Interface Model for Static/Flowing Dynamics in Thin-Layer Flows of Granular Materials with Yield: Simple Shear Simulations and Comparison with Experiments

“…These promising results may be related to the use of a coarse mesh, whereby simulations avoid the ill-posedness by damping the fast-growing high wavenumbers [33]. In any case, the quasi-static regime near the static/flowing interface is known to be very complex, involving strong and weak force chains and local rearrangement of particles, e.g., [36,37] and has been widely studied, in particular using discrete element methods, e.g., [1,38,39]. This regime is not accurately described by the proposed viscoplastic laws involving a simple yield stress.…”