ABSTRACT
This chapter reviews methods where visualization is provided by means of a suitable coating of the surface of bodies in the flow; the fluid flowing around the body changes the coating, allowing determination of certain flow characteristics. Chemical methods based on chemical reactions are used commonly for visualization of liquid flow. The liquid used is usually water, and it is hard to find a substance that would react suitably with water. This problem is solved by adding to the water a chemical substance that reacts with a reagent in the coating of the body in flow. Physical methods are used more frequently than chemical methods during the flow of water around a body. The following substances were tested as a base of the coating: acetoacetanilide, exalgine, acetanilide, phenacetine, hydro-quinone diacetate, and benzoine. When using mechanical methods of visualizing liquid flow on the surface of bodies, preparation of the surface is very simple.
