Flow visualization

Overview

Methods of visualization

• Surface flow visualization: This reveals the flow streamlines in the limit as a solid surface is approached. Colored oil applied to the surface of a wind tunnel model provides one example.
• Particle tracer methods: Particles, such as smoke or microspheres, can be added to a flow to trace the fluid motion. We can illuminate the particles with a sheet of laser 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 the particle image velocimetry or particle tracking velocimetry methods. Particles with densities that match that of the fluid flow will exhibit the most accurate visualization.
• Optical methods: Some flows reveal their patterns by way of changes in their optical refractive index. These are visualized by optical methods known as the shadowgraph, schlieren photography, and interferometry. More directly, dyes can be added to flows to measure concentrations; typically employing the light attenuation or laser-induced fluorescence techniques.

• Analytical methods that analyse a given flow and show properties like streamlines, streaklines, and pathlines. The flow can either be given in a finite representation or as a smooth function.
• Texture advection methods that "bend" textures according to the flow. As the image is always finite, these methods will visualize approximations of the real flow.

  Application