Selected Works . Volume 2. Hydrodynamics. The problems of flow and outflow, aerodynamic design” by Sergey Betyaev is a unique publication that immerses the reader in the deep and complex aspects of hydrodynamics and aerodynamics. This volume is a continuation of the series in which the author shares his extensive knowledge and experience in the field of fluid and gas mechanics, as well as the design of aerodynamic objects. Sergey Betyaev is an outstanding scientist and practitioner, whose works are known not only in Russia, but also abroad. He is the author of many scientific papers exploring various aspects of mechanics, and this volume is no exception. The book explores the key challenges associated with body flow and outflow, which is of great importance for many areas of science and technology, including aviation, automotive and shipbuilding. The reader who opens this book will find in it not only theoretical foundations, but also practical examples that will help to better understand complex concepts. Betyaev masterfully combines a scientific approach with an accessible language, which makes his work attractive for both undergraduate and graduate students and for experienced professionals seeking to deepen their knowledge in the field of hydrodynamics and aerodynamics. The book will be especially interesting for those who are fond of engineering, physics and mathematics. Students of technical universities, graduate students, as well as practicing engineers and researchers will find in this publication a lot of useful information. Betyaev raises important topics, such as the influence of body shape on its flow, methods of numerical flow modeling and aerodynamic design, which makes the book relevant to modern realities. One of the key topics addressed in the book is the interaction of flow with the surface of the body, which is critical for the design of aircraft and cars. Betyaev not only explains the theoretical aspects, but also offers practical solutions that allow the reader to apply the knowledge gained in real practice. This makes the book not just a textbook, but a real reference for engineers and scientists. Betyaev's style is distinguished by clarity and logical presentation, which allows the reader to easily assimilate complex concepts. He knows how to present material in such a way that even the most confusing topics become understandable and accessible. This quality makes his works in demand and popular with a wide audience. In addition to this volume, readers can get acquainted with other works by Betyaev, which are also devoted to the mechanics of liquids and gases. His previous publications and articles have already won recognition in scientific circles, and this volume continues the tradition of high-quality scientific presentation. Thus, "Selected Works. Volume 2. Hydrodynamics. The problems of flow and outflow, aerodynamic design" is not just a book, but a real find for anyone interested in aerodynamics and hydrodynamics. It combines theory and practice, making it an indispensable source of knowledge for students, engineers and scientists. If you are looking for a deep understanding of the processes taking place in the streams and want to learn how this knowledge is applied in real projects, this book will be your reliable assistant along the way.