WIT Press is pleased to announce publication of Computational Methods in Multiphase Flow VI. The book contains the papers presented at the Sixth International Conference on Computational and Experimental Methods in Multiphase and Complex Flow. The biennial series of conferences focuses on combining experimental and computational techniques to gain a better understanding of individual classes of multiphase flow. Multiphase flows are becoming increasingly important in many areas: manufacturing, minerals extraction, environmental remediation, and medicine to name just a few. And technological advances are constantly occurring. Although experimental, theoretical and computational efforts in the field have spanned decades, we still do not fully understand the complex behaviors inherent in multiphase flows. For several reasons, it is difficult to formulate accurate models even for the simplest of systems. There is the interaction of phenomena occurring at several different length scales, which in general cannot be decoupled from one another. At the smallest (nano) scales, processes occur that are neither continuum nor molecular, and therefore cannot be treated either at the molecular level (the problem is too big) or at the continuum level (the model may miss important non-continuum effects). Examples of such situations are interface phenomena at engineered interfaces which involve both a vapor and a liquid phase, or surface-to-surface interactions via an intervening fluid. One length scale up (micro), structure formation can cause difficulties in formulating boundary conditions and constitutive equations. Most investigators have approached the problem by applying direct numerical simulation at some level, and using models or approximations to treat smaller-scale phenomena, with the ultimate aim of finding out enough about the flow behavior to be able to construct a constitutive model that captures the essential physics. At present, one theory fits everything is not a viable option because of the many possible combinations of flow parameters. Therefore, it is still necessary to categorize multiphase flow problems into various categories (e.g. bubbly flows, fluidized beds, suspensions). Within each of these categories, it is possible to develop accurate descriptions of the flows. The papers in this volume contribute to the body of knowledge on the topic.