Computational Models for Turbulent Multiphase Reacting Flows
July 3, 2006 — July 7, 2006
- Rodney O Fox (Iowa State University, Ames, Iowa, USA)
- Daniele Marchisio (Politecnico di Torino, Torino, Italy)
The detailed simulation of turbulent multiphase reacting flows is of paramount importance for design, optimization, and scale-up of relevant processes, such as: turbulent combustion, diesel engines, fluidization and particle technology, crystallization and precipitation processes. There are many aspects that need to be taken into account in order to properly model such flows. The fluid-dynamic interaction between the primary and secondary phases is a key factor, in fact, it determines turbulence intensity, mixing rates, and mass and heat transfer. In the case of reacting multiphase flows, this interaction has a strong influence on reaction rates that, in turn, can heavily affect the flow field (e.g., combustion). Another key factor is the evolution of the secondary phases. In turbulent multiphase reacting flows the secondary phases are very often poly-disperse, or in other words, are distributed over several important properties such as characteristic size, composition, and temperature. The distribution continuously evolves because of the chemical reactions and fluid motion, but in turn the distribution itself strongly influences the flow and turbulence fields and has a strong impact on the chemical reactions.
The course aims to describe the most widely applicable modeling approaches and it is organized in six groups of lectures covering from fundamentals to relevant applications. In the first part of the course, some fundamentals of multiphase turbulent reacting flows are covered. In particular the introduction focuses on basic notions of turbulence theory in single-phase and multi-phase systems as well as on the interaction between turbulence and chemistry. In the second part of the course, models for the physical and chemical processes involved are discussed. Among other things, particular emphasis is given to turbulence modeling strategies for multiphase flows based on the kinetic theory for granular flows. Next, the different numerical methods based on Lagrangian and/or Eulerian schemes are presented. In particular the most popular numerical approaches of computational fluid dynamics codes are described (i.e., Direct Numerical Simulation, Large Eddy Simulation, and Reynolds-Averaged Navier-Stokes approach). The course will cover particle-based methods such as lattice-Boltzmann and dissipative particle dynamics and will also discuss Eulerian-Eulerian and Eulerian-Lagrangian techniques based on finite-volume schemes. Moreover, the possibility of modeling the poly-dispersity of the secondary phases in Eulerian-Eulerian schemes by solving the population balance equation will be also discussed.
The course is addressed to master and PhD students in engineering and science, post-docs and industrial researchers working on simulation and modeling of multiphase systems, such as: bubble columns, fluidized beds, aerosol, spray combustion chambers, crystallization and precipitation etc.