ABSTRACT
This chapter focuses on direct experimental visualization of flow. It reviews contemporary flow-visualization principles and methods and time-tested methods that continue to be very useful. The chapter presents fundamental principles behind the application and interpretation of flow visualization, and introduces several advanced techniques used in water, while providing citations for more in-depth study. It also presents flow visualization by the methods that usually involves selectively marking water with a passive tracer, illuminating the tracer, imaging the light scattered by the tracer, and interpreting the resulting patterns. Tracers added to the flow for water flow visualization consist of either suspended particles or bubbles, or aqueous dye solutions. The two types of image sensors found in scientific or consumer-grade cameras for flow visualization are charge coupled devices and complementary metal oxide semiconductors. Three-dimensional flows often are distinguished by lines of flow separation and attachment that delineate distinct regions of the flow are important for characterizing the flow structure.
