Alien Registration- Dugal, Armand G. (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/31225/thumbnail.jp

Slow flows of yield stress fluids: complex spatio-temporal behaviour within a simple elasto-plastic model

A minimal athermal model for the flow of dense disordered materials is proposed, based on two generic ingredients: local plastic events occuring above a microscopic yield stress, and the non-local elastic release of the stress these events induce in the material. A complex spatio-temporal rheological behaviour results, with features in line with recent experimental observations. At low shear rates, macroscopic flow actually originates from collective correlated bursts of plastic events, taking place in dynamically generated fragile zones. The related correlation length diverges algebraically at small shear rates. In confined geometries bursts occur preferentially close to the walls yielding an intermittent form of flow localization.Comment: 4 pages, 4 figure

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https://digitalcommons.library.umaine.edu/mmb-vp/2779/thumbnail.jp

Thermo-poro-mechanical coupled processes during thermal pressurization around nuclear waste repository

This paper investigates the thermo-hydro-mechanical behavior of Callovo- Oxfordian claystone, a potential host formation for prospective nuclear waste disposal in France. Thermal pore pressure appears in low permeability soils and rocks due to the difference between the thermal expansion coefficients of water and the argillaceous skeleton, as well as the low permeability of the media and the its relative rigidity, which prevent dissipation of the fluid pressure. Coupled thermo-hydro-mechanical numerical analyses have been carried out to enhance the understanding of the Callovo-Oxfordian claystone behavior subjected to heat emitted from radioactive waste that diffuses through the near-field rock to the far-field. In this view, the “thermal pressurization coefficient”, defined as the increase of pore pressure due to 1°C increase of temperature, was calculated. This coefficient depends on the nature of the rock, i.e the thermo-poro-mechanical parameters such permeability, Biot’s coefficient, rigidity, thermal conductivity as well as their anisotropies. Finally, the effect of parameters’ variability on the thermal pressurization coefficient is discussed through a sensibility analysis

Micro-evaporators for kinetic exploration of phase diagrams

We use pervaporation-based microfluidic devices to concentrate species in aqueous solutions with spatial and temporal control of the process. Using experiments and modelling, we quantitatively describe the advection-diffusion behavior of the concentration field of various solutions (electrolytes, colloids, etc) and demonstrate the potential of these devices as universal tools for the kinetic exploration of the phases and textures that form upon concentration