The overarching goal of our lab is to develop general frameworks to describe the dynamics of multiphase systems in various environments, for instance, when confined by interfaces or solid surfaces, when particles cross a fluid-fluid interface, or when some phase change occurs due to heat transfer or chemical processes. We also aim to account for the possible complex nature of the particles (cohesive, flexible, porous, ...). . Our research activities generally entail multiphase systems, such as suspensions of particles, granular materials, immiscible fluid mixtures, droplets, polymers, and solid/liquid/gas phases of the same component. These systems are particularly exciting as they share common features and are involved in numerous situations, from industrial processes to environmental situations. Despite that these systems are common in day-to-day life, they remain poorly understood. Below is a (non-exhaustive) list of current projects our group is working on.
Capillary flows of complex fluids
When a liquid phase contains solid particles, emulsion droplets, or gas bubbles, the classical interfacial dynamics and rheological approaches commonly fail to describe the interfacial dynamics involved in the formation of droplets and thin films. Our group relies on an experimental approach bridging different length and time scales to decouple the influence of the bulk behavior and the local heterogeneities brought by the particles on the dynamics of capillary objects. The fundamental knowledge obtained through this work aims at a better description of capillary flows involving a solid dispersed phase during the formation, flow, and fragmentation of suspension threads, thin films and sheets, and drops. We also consider the influence of complex rheology, for instance, for viscoelastic liquids. Such a configuration is important for a broad range of industrial and environmental processes: spray coating, dip coating, additive manufacturing, two-phase flow of suspensions in soil, and porous media, among others. In addition to improving the efficiency of industrial processes, the knowledge obtained should bolster the development of new coating processes leveraging capillary effects.
Transport and clogging of particles in complex environments
The aggregation of particles and resulting clog formation in confined systems, such as pipes or arteries, have dramatic consequences. When a clog is formed, the particles are no longer transported, and the fluid is transported at a low flow rate. Clogging of a channel can occur through direct obstruction by large particles or fibers (sieving), by forming a bridge (jamming), or by the continuous deposition of microparticles on a channel (aggregation). In filters, this leads to a reduction of the volume filtered. In blood vessels, clogs prevent oxygen from reaching a section of the vascular system. Even at larger scales, clogging occurs. This was demonstrated recently by the blockage of the Suez channel by a container ship that cost an estimated $9.6 billion of trade along the waterway each day. Predicting the dynamics associated with clogging requires modeling the coupling between particles, fluid, and boundaries. However, our understanding of clog formation and prevention is, at best, qualitative and limits the development of resilient systems. Our goal is to characterize, describe and predict the occurrence of clogging in such systems, and engineer innovative methods to prevent or delay clogging.
Phase change, Heat transfer, Reactive Flow
Heat transfer and phase change, such as observed during drying, are important phenomena that play a critical role in a variety of industrial processes. For instance, when drying powders, or fiber networks, the removal of moisture can lead to agglomeration between particles. The rate of heat transfer and the amount of energy required for the phase change depend on the properties of the system, such as its composition, the temperature, the relative humidity, etc. Similarly, in the process of ice formation, the transfer of heat from the surrounding environment to the water causes it to freeze, in which case air bubbles can be trapped in the resulting ice. Modeling these phenomena is crucial in industries such as food processing, pharmaceuticals, and materials science, where the control of heat transfer, phase change, and mechanical input, can significantly impact product quality and efficiency. Our group is currently investigating the drying of powders under shear and the coupling between fluid flow and ice formation.
Influence of cohesion on granular and particle transport
We aim to describe the dynamics of cohesive particulate matter such as grains subject to biological cohesion, dust, powders, snow, or clay. Whereas the last few decades have seen substantial progress in our ability to predict the dynamics of non-cohesive particles, comparable progress has not yet been achieved for cohesive grains. An accurate description of cohesive particles is crucial as the erosion and transport of cohesive materials play a dominant role in numerous industrial applications (handling of powders) and also for a wide range of environmental processes (aeolian soil erosion, erosion by aircraft engines, transport of sediment in oceans and rivers). At present, our understanding of these processes is qualitative at best, and in particular, the influence of biocohesion in submarine particulate flows remains elusive. Accurate modeling requires a quantitative knowledge base, and in particular, the formulation of reliable scaling laws.
From dry to wet granular material
Granular materials are ubiquitous in many industrial and geophysical processes. Our goal is to describe how dry grains enter into water and lead to a suspension of particles. Although over the past two decades different studies on dry and wet granular media have brought new approaches in their modeling, the transition between these two regimes remains unclear and empirical. This situation encompasses industrial applications (blending of grains and liquid), as well as geophysical processes (tsunami waves generated by landslides, initiation of mudflow), and environmental engineering (irrigation). Understanding how dry grains can get disperse into water to obtain a suspension of particles is a challenging task because of the three phases involve (grains, liquid, air).
