Particles in Wall-Bounded Turbulent Flows: Deposition, Re-Suspension and Agglomeration
September 14, 2015 — September 18, 2015
- Jean-Pierre Minier (EDF R&D, MFEE, Chatou, France)
- Jacek Pozorski (IMP, Polish Academy of Sciences, Gdansk, Poland)
Particle transport in nearwall turbulent flows involves challenging phenomena, such as deposition, re-suspension and agglomeration, which cover a wide range of situations from single-particle deposition to the formation of deposited aggregates that modify fluid flows. These issues have implications in many processes ranging from power-generation industries to electronics, food industry, water treatment, micro-mechanics and micro-biology and are also found in environmental or medical contexts.
What is referred to as ‘particle deposition’ is best addressed by introducing a coupling between the underlying phenomena (deposition, re-suspension, agglomeration, clogging) which reveals that three fundamental physical interactions are at play: particle/fluid, particle/surface and particle/particle interactions. There are thus two major mechanisms: the hydrodynamic transport, describing particle/ fluid interactions and how particles are transported and dispersed by turbulent flows, and the attachment mechanism, describing particle/surface and particle/particle interactions and how particles adhere to surfaces. The related phenomenology has often been addressed from two separate points of view using: either a hydrodynamic approach but with a poor description of attachment forces or a physicochemical standpoint but with no proper account for particle transport. However, new descriptions have emerged with the development of multi-scale models. Furthermore, new insights have been provided by Direct Numerical Simulation (DNS) and by fine experimental techniques (such as PIV/PTV or AFM), leading to an improved understanding of particle deposition.
With respect to this context, the course has a three-fold objective:
– To provide an in-depth presentation of the phenomenology involved in particle dynamics in wall-bounded turbulent flows and of the basic physical interactions;
– To introduce unified models of particle deposition (which combine hydrodynamic and physico-chemical approaches) that are helpful to achieve a comprehensive description of the complete phenomenon;
– To discuss open experimental/ modelling issues, for example multi-layer deposition and resuspension.
The general terminology of ‘particles’ does not mean that the course will be strictly limited to solid (colloidal or inertial) spherical particles. Indeed, specific lectures will also discuss droplets (coalescence/breakup) and non-spherical particles, such as fibre suspensions in turbulent flows. The course is organised so as to cover the different aspects of the physics involved in particle behaviour in turbulent flows (thus, the transport/attachment mechanisms) and the variety of points of view (experimental/ numerical/modelling).
The present course will be attractive to graduate and doctoral students, to young researchers as well as to practicing engineers in the fields of mechanical, nuclear, environmental, medical, chemical and process engineering. Since the course includes presentations of up-to-date progress as well as open questions that remain to be addressed, it will be also of interest for senior researchers.