Foreword

Dispersed flows with droplets and particles abound in nature from clouds, mist and fogs to the long-range transport of fine dust released in desert storms or in volcanic eruptions. They control the weather and influence the climate. They play key roles in many industrial energy processes – from spray drying, pneumatic conveying and fluidized beds, to coal gasification and mixing and combustion processes. They can have a profound effect on our health and quality of life, e.g. the inhalation of very fine air-borne particulate (PM10s) damages respiratory functions, and lead to increased cardio- pulmonary mortality rates and allergic disorders. Understanding the behavior of these flows, through modeling and experiment, is therefore important in our control of the environment, improving our health, and in the design and improvement of industrial processes.

There are essentially two ways of modeling dispersed flows, the Euler-Lagrange (E-L) approach where individual particle are tracked through an Eulerian flow field or an entirely Eulerian (E-E) approach where both the dispersed and continuous phases are described by a set of continuum equations that represent the conservation of mass moment and energy within an elemental volume of the mixture. This e-Book is about the E-L approach and exploits the recent advances in modeling complex flows in which LES has been used to describe the underlying large scale features of the continuous phase and stochastic equations based on the Generalized Langevin equations for the sub-filtered (SGS) motion of the fluid seen by the particle. The main advantage of this approach is that one can deal very successfully with particle dispersion and transport in complex industrial flows with complex geometries and boundary conditions, noting also that much success has been achieved using this approach in more generic flows like deposition of particles in a turbulent boundary. The author has been successful in presenting a thoroughly comprehensible and readable text that engineering researchers can use as a source of reference as well as for fundamental understanding. In order to achieve the dual objectives of understanding and simplicity, lengthy mathematical analysis has been avoided and emphasis has been placed on detailed applications. In view of the recent advances in LES and sub grid scale modeling and the application of stochastic methods, a e-Book of this nature is very timely and one that I would thoroughly recommend to all young researchers embarking on a study of industrial dispersed flows.

Michael W. Reeks
Professor of Multiphase Flows
Newcastle University
U.K