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Towards numerical simulation of flows laden with particles of arbitrary shape Wachs, Anthony


Talk: Plenary Abstract: Particulate flows are ubiquitous in environmental, geophysical and engineering processes. The intricate dynamics of these two-phase flows is governed by the momentum transfer between the continuous fluid phase and the dispersed particulate phase. When significant temperature differences exist between the fluid and particles and/or chemical reactions take place at the fluid/particle interfaces, the phases also exchange heat and/or mass, respectively. While some multi-phase processes may be successfully modelled at the continuum scale through closure approximations, an increasing number of applications require resolution across scales, e.g. dense suspensions, fluidized beds. Within a multi-scale micro/meso/macro-framework, we develop robust numerical models at the micro and meso scales, based on a Distributed Lagrange Multiplier/Fictitious Domain method and a two-way Euler/Lagrange method, respectively. Collisions between finite size particles are modeled with a Discrete Element Method. Many real-life processes and/or flows involve non-spherical particles. Although there is still a lot to learn about flows laden with spherical particles, there is also a strong incentive to develop new modeling tools to account for non-spherical, angular, convex or even non-convex particles. At the micro scale, the main challenge is the modeling of collisions. At the meso scale, the consideration of non-spherical particles implies to derive appropriate closure laws for hydrodynamic interactions. For the former, we describe the numerical ingredients of our granular solver that handles both convex and non-convex particles. The latter is an open field in the literature. The classical two-way Euler/Lagrange approach for spherical particles normally extends straightforwardly to non-spherical particles, provided the particle aspect ratio is not too large. However, the determination of the dominant part of the hydrodynamic interaction and of the corresponding closure laws has not received a significant attention from the community so far. Finally, we shortly discuss some of the high performance computing issues related to our massively parallel numerical tools and illustrate their modeling capabilities on the two following problems relevant of applications from the chemical engineering and process industry: (i) a rotating drum filled with non-convex particles and (ii) fixed and fluidized beds of multilobic (and hence non-convex) particles.

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