This volume is dedicated to a very special person, Professor Gad Hetsroni (1934-2015). His towering figure was familiar to researchers in heat transfer and multiphase flow all over the world. He was the founding Editor of the International Journal of Multiphase Flow and the person who defined and promoted the discipline around the journal. The unique community formed in this field during his lifetime gathers every three years for a major conference, the International Conference on Multiphase Flow, that most recent was held in May 2016 in Florence, Italy. This was the first time ever Gad did not attend ICMF. Friends and colleagues from many countries came to Florence to present their personal tributes and scientific papers honoring Gad. Reviewed and edited tributes and scientific papers dedicated to Gad from these memorial sessions comprise the core content of this memorial volume; certain persons who could not participate in the ICMF made later contributions.

This book is the maiden volume in a new series devoted to lectures delivered through the annual seminars “Short Courses on Multiphase Flow,” held primarily at ETH Zurich continuously since 1984. The Zurich short courses, presented by prominent specialists in the various topics covered, have attracted a very large number of participants. This series presents fully updated and when necessary re-grouped lectures in a number of topical volumes. The collection aims at giving a condensed, critical and up-to-date view of basic knowledge on multiphase flows in relation to systems and phenomena encountered in industrial applications. The present volume covers the background of Multiphase Flows (MPF) that introduces the reader to the particular nature and complexity of multiphase flows and to basic but critical aspects of MPFs including concepts and the definition of the quantities of interest, an introduction to modelling strategies for MPFs, flow regimes, flow regime maps and tr ansition criteria. It also deals with the ubiquitous needs of the multiphase-flow modeller, namely pressure drop and phase distribution, i.e., the void fraction and the topology of the phases that determines the flow regimes.

Dispersed multiphase flows are frequently found in nature and have diverse geophysical, environmental, industrial, and energy applications. This book targets a beginning graduate student looking to learn about the physical processes that govern these flows, going from the fundamentals to the state of the art, with many exercises included.