Bedload, the coarser material transported in contact with the bed by turbulent flow in stream channels, has major consequences for public safety, water resources, and environmental sustainability. Size sorting also named size segregation is responsible for our limited ability to predict sediment flux and river morphology, especially in mountains where steep slopes drive an intense transport of...
In the context of modeling two-phase debris flows involving grains and fluid, some shallow water systems arise with internal variables.
Our work focus on such a shallow water system with two internal variables and a topography $b$ which adds a nonconservative term. \
For numerical purposes, it is desirable to deal with a system where the mathematical entropy (the physical energy of...
The granular column collapse is a benchmark experiment for studying granular flows. Granular flows are found in varying scales from handling purposes to natural debris flows and can occur in subaerial or submerged environments. Out of convenience, granular flows are commonly studied with a monodisperse distribution of grains; however, the variety of grain sizes, known as polydispersity, is an...
Constitutive laws for viscoplastic materials involve a multivalued nonlinearity. Duality methods for such equations are known to converge, but the convergence is slow, the error is in general of the order of $1/k$ with $k$ the number of iterations.
We consider here an iterative method of classical implicit primal-dual type with a particular form with strong implicitation. An analysis via...
Dans l’étude numérique [1], nous avons fourni une condition aux limites pour les écoulements granulaires s'écoulant sur des bords lisses. Nous avons montré qu'il existe une loi universelle reliant le coefficient de frottement effectif local à un nombre de Froude local 〖Fr〗_loc=V⁄√(P⁄ρ) (où V et P sont respectivement la vitesse et la pression locales à la frontière, et la masse volumique des...
Un modèle non moyenné prenant en compte la pression du gaz interstitiel, ici de l'air, dans un milieu granulaire dense est présenté. IL est obtenu à partir des équations de Jackson modélisant un mélange fluide-solide. L'équation de la quantité de mouvement du fluide interstitiel est simplifiée de telle sorte que l'équation de conservation de la masse de ce dernier permet d'écrire une équation...
The dynamics of geophysical dilute turbulent gas-particles mixtures depends to a large extent on particle concentration, which in turn depends on the particle settling velocity. In the first part of this talk, we present the experimental investigation of dilute air-particle mixtures by acoustic probing and air pressure measurements. We show hat there are two settling mechanisms depending on...
Les précurseurs d'avalanche sont de petits déplacements de surface quasi-périodiques, observés expérimentalement lors de l'inclinaison lente d'un lit granulaire. L'avalanche apparaît dans la séquence des précurseurs, comme le point culminant d'une séquence d'événements qui le procède. Une compréhension des précurseurs éclairerait donc le déclenchement des écoulements granulaires.
Une...
Dense granular flows can spontaneously self-channelise by forming a pair of parallel-sided static levees on both sides of a central flowing channel. This process prevents lateral spreading and maintains the flow mobility for longer, enabling the avalanche to run out considerably further than a spreading flow. Since levees commonly form in hazardous geophysical mass flows, such as snow...
The dynamics of geophysical dilute turbulent gas-particles mixtures depends to a large extent on particle concentration, which in turn depends on the particle settling velocity. In the first part of this talk, we present the experimental investigation of dilute air-particle mixtures by acoustic probing and air pressure measurements. We show hat there are two settling mechanisms depending on...
