This book is targeted to graduate students and researchers at the cutting edge of investigations into the fundamental nature of multiphase flows. It is intended as a reference book for the basic methods used in the treatment of multiphase flows. The subject of multiphase flows encompasses a vast field whose broad spectrum presents a problem for the experimental and analytical methodologies that might be appropriate for the reader's interests. The aim of Fundamentals of Multiphase Flow is to bring much of this fundamental understanding together into one book, presenting a unifying approach to the fundamental ideas of multiphase flows. The book summarizes those fundamental concepts with relevance to a broad spectrum of multiphase flows. It does not pretend to present a comprehensive review of the details of any one multiphase flow or technological context; references to such reviews are included where appropriate.