Techniques of flow visualization

The methods of flow visualization are reviewed with particular emphasis on their application in wind tunnels, water tunnels, and experiments related to propulsion research. The discussion of methods starts with those that visualize the flow pattern on a solid surface. Then methods visualizing the whole field, either by introducing a foreign substance (smoke, dye) or by making use of refractive index changes in the flowing fluid (optical methods) are examined. Emphasis is placed on the discussion of the physical background of a method rather than on technical details.