Stagnation Points as Loci of Solute Concentration Extrema at the Evaporative Surface of a Random Porous Medium

Transport in Porous Media - Evaporation of a saline solution from a porous medium often leads to the precipitation of salt at the surface of the porous medium. It is commonly observed that the...     

Optimisation of Gas Access Through a Thin Porous Layer with a Partially Occluded Inlet Surface

Transport in Porous Media - The gas access through a thin porous layer is studied in relation to the reactant gas transfer in the gas diffusion layer (GDL) of polymer electrolyte membrane fuel...     

Some recent advances in the design and the use of miniaturized droplet-based continuous process: applications in chemistry and high-pressure microflows

This mini-review focuses on two different miniaturizing approaches: the first one describes the generation and use of droplets flowing within a millifluidic tool as individual batch microreactors. The second one reports the use of high pressure microflows in chemistry. Millifluidics is an inexpensive, versatile and easy to use approach which is upscaled from microfluidics. It enables one to produce hierarchically organized multiple emulsions or particles with a good control over sizes and shapes, as well as to provide a convenient data acquisition platform dedicated to slow or rather fast chemical reactions, i.e., from hours to a few minutes. High-pressure resistant devices were recently fabricated and used to generate stable droplets from pressurized fluids such as supercritical fluid-liquid systems. We believe that supercritical microfluidics is a promising tool to develop sustainable processes in chemistry.     

On Ions Transport during Drying in a Porous Medium

Salt crystallisation at the surface or in a porous medium has been recognised as a major mechanism of deterioration of buildings and historical monuments. Often crystallisation occurs when the concentration of salt dissolved in the water contained in the porous medium reaches the saturation concentration as the result of evaporation. In order to predict the evolution of the ion distribution during drying, we develop a simple volume averaged model combining a semi-analytical model of drying with the numerical computation of the ions transport. The model is used to analyse the influence of the drying rate, size of the porous medium, average pore size and initial ion concentration on the ion distribution during drying and therefore the possible location of crystallisation.