Flow visualization orflow visualisation influid dynamics is used to make theflow patterns visible, in order to get qualitative or quantitative information on them.
Flow visualization is the art of making flow patterns visible. Mostfluids (air, water, etc.) aretransparent, thus their flow patterns are invisible to the naked eye without methods to make them this visible.
Historically, such methods included experimental methods. With the development of computer models andCFD simulating flow processes (e.g. the distribution of air-conditioned air in a new car), purely computational methods have been developed.
Surface flow visualization: This reveals the flowstreamlines in the limit as a solid surface is approached. Colored oil applied to the surface of awind tunnel model provides one example (the oil responds to the surfaceshear stress and forms a pattern).
Particle tracer methods: Particles, such as smoke ormicrospheres, can be added to a flow to trace the fluid motion. We can illuminate the particles with a sheet oflaser light in order to visualize a slice of a complicated fluid flow pattern. Assuming that the particles faithfully follow the streamlines of the flow, we can not only visualize the flow but also measure its velocity using theparticle image velocimetry orparticle tracking velocimetry methods. Particles with densities that match that of the fluid flow will exhibit the most accurate visualization.[1]
Analytical methods that analyse a given flow and show properties likestreamlines, streaklines, and pathlines. The flow can either be given in a finite representation or as a smooth function.
Texture advection methods that "bend" textures (or images) according to the flow. As the image is always finite (the flow through could be given as a smooth function), these methods will visualize approximations of the real flow.
Incomputational fluid dynamics the numerical solution of the governing equations can yield all the fluid properties in space and time. This overwhelming amount of information must be displayed in a meaningful form. Thus flow visualization is equally important in computational as in experimental fluid dynamics.
