This session will bring together researchers involved in all aspects of mathematical modelling of flows with high geomorphic potential, herein “geomorphic flows”. This category includes all flows of mixtures of fluid and sediment (two-phase flows) that cause significant morphological changes and occur at or generate high internal stresses on both phases. A non-exhaustive list would include surface flows of solids such as rock or snow avalanches, flows of granular-fluid mixtures such as sheet flows in hillslopes or rivers in the upper regime, lahars or other mudflows, debris flows or tsunamis propagating overland. The concept can be extended to include lava flows. Most geomorphic flows are a consequence of natural hazards. Yet, anthropic causes are at the root of dam-break or dam-breach flows, which are highly formative and capable of considerable geomorphic impacts.
There is no universal description of geomorphic flows. The characteristic grain diameter and the volume fraction of the granular phase, itself a flow variable, strongly influence the perceived macroscopic properties of the flow of both phases. Hence, geomorphic flows may exhibit different behaviours, from fluid-dominated Newtonian to complex rheologies determined mostly by grain interactions.
Research involving kinematics and dynamics of granular media has traditionally been determined by its ultimate applications, either industrial or in the realm of applied earth sciences. It has thus been scattered across disciplines dealing with geomorphology, including in the coastal or river domains and at several scales, or industrial granular media. Within each discipline there have been outstanding achievements, mostly at engineering working scales. In the process, it has been discovered that the structure of the laws describing the macroscopic aspects of many geomorphic flows are, in most cases, relatively simple and can be devised through a judicious combination of dimensional analysis, laboratory work and field investigation. This fact associated too the increase of computational capacity, ingluding advances in parallelization and GPU computing, has allowed major progresses in what concerns computing solutions to particular problems.
Yet, it is our belief that faster advances can be achieved if modelling experiences of different geomorphology branches are shared and discussed in a same forum, thus promoting the harmonization of the vocabulary, premises, mathematical and numerical techniques to tackle key theoretical and computational issues. These include conceptual description (formulation of conservation and closure equations, mathematical properties of the system of conservation laws), numerical discretization techniques (mesh-based methods, meshless methods) and implementation strategies (CPU, GPU). Flows of interest include (but are not restricted to):
- rock, soil or snow avalanches;
- mud and debris flows;
- debris laden tsunami run-up ;
- dam-break flows and other anthropic geomorphic flows;
- flash floods;
All scales of work are welcome, from detailed granular and granular-fluid interaction to bulk description of mass movements, and from full three-dimensional modelling to one-dimensional approaches.