This book presents the results of scientific research performed over the past two decades by the authors. The book discusses some issues of separated laminar flows that are of great practical interest for the development of new technologies using microchannel flows, where separation zones can form. Of particular interest is the complex mechanism of flow separation with superimposed high external turbulence. The challenges of finding the optimal location for the cavities and fins on heat exchange surfaces are also considered. This is an important fundamental and practical problem when creating new schemes of efficient heat exchangers in various power plants. A wide class of problems of turbulent flow in tubes with flow separation is considered. These data will be useful in engineering estimates of the thermal-hydraulic efficiency of various heat transfer intensifiers. This book focuses on the analysis of thermal characteristics of separated flows, as well as the possibility of controlling the intensity of heat exchange processes, from the point of view of both their intensification and their suppression.