The monograph discusses issues related to the use of the results of visualization of optically active fluid flows in the channels of heat exchange and technological devices and devices. Photos of pictures of the current are given. Particular attention is paid to the development of models of the potential flow of incompressible fluid and their analysis based on the results of flow visualization. Based on experimental studies and data from other authors, examples of using imaging results for profiling the walls of channels of various devices and devices are considered. Designed for specialists involved in solving theoretical and applied problems in hydrodynamics, heat and mass transfer.