|09.30||Coffee and registration|
Recent advances in the multi-scale simulation of mass, momentum and heat transfer in dense gas-particle flows
Dense gas-particle flows involving momentum, mass and heat transfer are frequently encountered in industrial processes involving granulation, coating and polymerization. In these flows both (effective) fluid-particle and (dissipative) particle-particle interactions need to be accounted for because (the competition between) these phenomena to a large extent govern the prevailing flow phenomena, i.e. the formation and evolution of heterogeneous structures. These structures have significant impact on the quality of the gas-solid contact and as a direct consequence thereof strongly affect the performance of the process. Additional complexities arise due to enhanced dissipation due to wet particle-particle collisions which prevail in processes such as spray drying, coating and granulation.
Due to the inherent complexity of these multiphase flows a multi-scale modeling approach is adopted in which both fluid-particle and particle-particle interactions can be properly accounted. The idea is essentially that fundamental models, taking into account the relevant details of fluid-particle interaction (DNS) and particle-particle interaction (DEM), are used to develop closure laws to feed continuum models (TFM) which can be used to compute the flow structures on a much larger (industrial) scale. In this presentation recent advances in the area of multi-scale simulation of dense gas-particle flows will be highlighted with emphasis on coupled mass, momentum and heat transfer. In addition, areas which need substantial further attention will be discussed.
|11.15||Stefan Luding||Fluid-Solid interactions for atoms and particles.|
The interactions of fluids and solids has many aspects and involves a multitude of mechanisms and phenomena at multiple scales. The focus of this presentation is on two of those:
1) the transition from a solid to a fluid (e.g. relevant for the release of avalanches and landslides) as well as the transition from a fluid to a solid-like behavior (related to jamming and shear-thickening in various materials like suspensions or soft and granular matter.
2) the interaction of the fluid with the solid boundaries, which leads to short-ranged ordering,
layering or cristallization, e.g. a wall-induced microstructure that renders the fluid behaving
much differently from a bulk-fluid due to the existence of this fabric/structure on the atomistic or particle scale.
The forces of surface tension are known to determine the shape of droplets and liquid menisci. In principle, elastic solid interfaces also exhibit a surface tension but its effect is usually not considered. In this lecture we will show how solid mechanics can be influenced, or even governed, by “solid capillarity”. Examples range from shape instabilities of very soft gels to the adhesion of nanoparticles. It will be discussed to what extent one can unify problems of liquid-wetting and solid-adhesion.
Recent extensions and advances in computational fluid-structure interaction
Fluid-Structure Interaction (FSI) problems, as well as many other coupled multi-field problems, have received much attention in recent years and continue to attract more interest. The main reason is that they are of great relevance to many fields of engineering (civil, mechanical, aerospace, bio, etc.) and applied sciences. Similarly, the development and application of corresponding numerical simulation methodologies have received wide attention over the past decades. Thanks to many advances in computational sciences and computing hardware, the numerical modeling and solution of a difficult subset of such problems that was thought to be unfeasible even five years ago, is either feasible today or will become feasible within the nearby future.
|15.45||Harald van Brummelen|
Modeling and simulation of multi-fluid-solid interaction
Multi-fluids are fluids that consist of multiple constituents, e.g. of multiple phases of the same fluid (liquid or gas) or of multiple distinct species (e.g. water and air). The interaction of such composite fluids with elastic solids leads to multitudinous intricate physical phenomena. In this presentation, we consider a computational model for multi-fluid--solid interaction based on a diffuse-interface model for the fluid. We consider various aspects related to fluid-solid surface tension and contact-line motion, and their
representation in the diffuse-interface fluid model. In addition, we will discuss specific aspects of the numerical solution procedure. We close with indicating challenges and open questions.