Simulation of granular flow in a rotating frame of reference using the discrete element method

Over the years, the Discrete Element Method (DEM) has attracted significant attention for its capacity to simulate granular flows because it captures physical phenomena that cannot be observed using continuum methods. However, the simulation of granular systems with DEM is computationally demanding, especially in the case of systems in rotation. One solution is to perform simulations in a non-inertial rotating frame of reference, which requires the addition of fictitious velocity-dependent forces such as the Coriolis force. We assess the numerical feasibility and accuracy of such DEM simulations. We show that the velocity Verlet scheme in its classical form no longer defines a symplectic map and is no longer of second order when there are velocity dependent forces. Nevertheless, our study of a dense particle flow within a rotating hourglass shows that the relevant properties of such flow are accurately reproduced in a non-inertial frame and that computational performance is improved

On the application of the factsage thermochemical software and databases in materials science and pyrometallurgy

ABSTRACT: The discovery of new metallic materials is of prime importance for the development of new technologies in many fields such as electronics, aerial and ground transportation as well as construction. These materials require metals which are obtained from various pyrometallurgical processes. Moreover, these materials need to be synthesized under extreme conditions of temperature where liquid solutions are produced and need to be contained. The design and optimization of all these pyrometallurgical processes is a key factor in this development. We present several examples in which computational thermochemistry is used to simulate complex pyrometallurgical processes including the Hall–Heroult process (Al production), the PTVI process (Ni production), and the steel deoxidation from an overall mass balance and energy balance perspective. We also show how computational thermochemistry can assist in the material selection in these extreme operation conditions to select refractory materials in contact with metallic melts. The FactSage thermochemical software and its specialized databases are used to perform these simulations which are proven here to match available data found in the literature

Modélisation de la viscosité des mélanges binaires et ternaires de liquides ioniques

RÉSUMÉ: Les liquides ioniques sont des sels avec un cation ou un anion organique, dont la température de fusion est typiquement inférieure à 100 °C. Ces liquides présentent de nombreux avantages par rapport aux solvants moléculaires organiques comme une faible tension de vapeur, et une bonne stabilité thermique et électrochimique. La variété des cations et des anions disponibles permet d’ajuster les propriétés d’un liquide ionique pour une application ciblée. Les mélanges de liquides ioniques augmentent le nombre de combinaisons possibles tout en étant plus simples à préparer.----------ABSTRACT: Ionic liquids are salts with an organic cation or anion, whose melting temperature is typically below 100°C. These liquids have many advantages over organic molecular solvents such as low vapour pressure, and good thermal and electrochemical stability. The variety of cations and anions available makes it possible to adjust the properties of an ionic liquid for a targeted application. Mixtures of ionic liquids increase the number of possible combinations while being easier to prepare

Physical properties and solid-liquid equilibria for hexafluorophosphate-based ionic liquid ternary mixtures and their corresponding subsystems

Mixing ionic liquids is a simple and economical method of exploiting their tunability and allows to use ionic liquids with high melting temperatures for low-temperature applications through the formation of eutectic mixtures. In this study, the phase diagrams of the [C4mpy][PF6]-[C4mpip][PF6]-[C4mpyrr][PF6] ternary system (where [C4mpyrr] = 1-butyl-1-methylpyrrolidinium; [C4mpy] = 1-butyl-3-methylpyridinium; [C4mpip] = 1-butyl-1-methyl-piperidinium) and all of its unary and binary subsystems were measured and modelled using the Modified Quasichemical Model and the Compound Energy Formalism for the liquid and relevant solid solutions, respectively. The phase diagram determination allowed for density and viscosity measurements over the entire composition range, from temperatures close to the liquidus up to about 110 °C. In addition, the thermal and physical properties of the ionic liquid [C4mim][PF6] ([C4mim] = 1-butyl-3-methylimidazolium) were measured. A new viscosity model was proposed to describe mixtures and was compared to the Grunberg-Nissan mixing law. The proposed model exhibited a better predictive ability for the viscosity data of ternary mixtures compared to the Grunberg-Nissan mixing law with the same number of adjustable parameters. The limits of the proposed viscosity model were analyzed in light of the Gibbs-Adam theory, using viscosity and configurational entropy data for [C4mim][PF6].publishe