Advances in Dispersed Multi-Phase Flows: from Measuring to Modeling
July 15, 2019 — July 19, 2019
- Filippo Coletti (University of Minnesota, Minneapolis, MN, USA)
- Remi Zamansky (Institut de Mécanique des Fluides de Toulouse, France)
Multi-phase flows where a dispersed phase interacts with a carrier fluid are ubiquitous in nature and industry, but the description of their dynamics has challenged scientists and engineers for decades. Difficulties arise due to the interface between the continuous and dispersed phases, the opacity of the media, and the vast range of spatial and temporal scales at play. However, recent developments in both measurement techniques and predictive capabilities bear the promise of a rapid progress in the near future. In this course, we will review existing theories that describe the behavior of this class of flows, and introduce a variety of measurement and simulation strategies that capture and reproduce the key phenomena.
Even in the idealized scenario of dilute suspensions of point-like particles, inertia leads to non-trivial behaviors, especially in the turbulent regime. Classic results on single-phase and particle-laden turbulence will be reviewed, as well as recent findings on multi-scale clustering and gravitational settling, especially relevant to natural phenomena. With increasing levels of concentration, we will illustrate how the two-way coupling between the phases becomes manifest, for both momentum and energy. Recent insight on the behavior of finite size particles of different shape and their interaction with the fluid will be also discussed. Bubbly flows display distinctive features due to the bubbles being often large and deformable, with gas-liquid interfacial dynamics and compressibility effects contributing to a rich phenomenology. We will review the fluid dynamics around individual and swarming bubbles, emphasizing the different types of agitation induced in the carrier liquid. Considering dense suspensions of particles or droplets in a liquid phase, we will introduce the fundamentals of rheology, highlighting the relation between the suspension structure and the macroscopic properties. We will also explore exciting developments on active dispersions, at the intersection of fluid mechanics and biology.
Throughout this course, we will critically assess modern numerical and experimental strategies. The former will include Eulerian methods with sharp and diffuse interfaces, and Lagrangian-Eulerian methods for rigid and deformable particles. Kinetic-based moment methods will also be addressed, stressing their connection with two-fluid methods and illustrating their versatility in technological applications such as polydisperse sprays. On the experimental side, we will address optics-based methods relying on particle imaging, but also powerful medical imaging modalities that can overcome the medium opacity.
The course is mainly directed to doctoral and postdoctoral students in engineering and physics, with strong interests in numerical simulations and experimental methods. It is also suited for researchers working in academia or R&D, interested in rapidly gaining a comprehensive overview of multiphase dispersed flows. The attendees will be encouraged to actively participate in the scientific conversation, also through a poster session in which they will present and discuss their own research. Matlab implementations of selected methodologies will be available for hands-on exercises.