Flow visualization


Flow visualization

In fluid dynamics it is critically important to see the patterns produced by flowing fluids, in order to understand them. We can appreciate this on several levels: Most fluids (air, water, etc.) are transparent, thus their flow patterns are invisible to us without some special methods to make them visible.

On another level, we know the governing equations of fluid motion (the Navier-Stokes equations), but they are nonlinear partial differential equations with very few general solutions of practical utility. We can solve them numerically with modern computer methods, but these solutions may not correspond to nature unless verified by experimental results.

On still another level the Navier-Stokes equations are pattern generators, and natural fluid flows display corresponding patterns that can recur on scales differing by many orders of magnitude. Such fluid patterns are familiar to almost everyone: the bathtub vortex and the tornado, the smoke ring and the mushroom cloud, the swinging of wires in the wind and the collapse of a historic bridge due to forced oscillations from vortex shedding.

Flow visualization is the art of making these patterns visible. In experimental fluid dynamics, flows are visualized by three methods: surface flow visualization, particle tracer methods, and optical methods. Surface flow visualization 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 (the oil responds to the surface shear stress and forms a pattern). Particles, such as smoke, 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 a method known as particle image velocimetry. Finally, 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.

In computational 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.

See also

* Streamlines, streaklines and pathlines

References

* Merzkirch, W., Flow visualization, New York:Academic Press, 1987.

* Van Dyke, M., An album of fluid motion, Stanford, CA:Parabolic Press, 1982.

* Samimy, M., Breuer, K. S., Leal, L. G., and Steen, P. H., A gallery of fluid motion, Cambridge University Press, 2004.

* Settles, G. S., Schlieren and shadowgraph techniques: Visualizing phenomena in transparent media, Berlin:Springer-Verlag, 2001.

External links

* [http://www.cg.tuwien.ac.at/~helwig/diss/node10.htm Flow visualization techniques] .
* [https://visualization.hpc.mil/wiki/index.php/Visualization_Algorithms Flow visualization algorithms] .
* [http://www.interactiveflows.com/links/ Educational Particle Image Velocimetry (e-PIV) - resources and demonstrations]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Visualization — The term visualization may refer to:* Creative Visualization * Educational visualization * Flow visualization * Geovisualization * Illustration * Information graphics, visual representations of information, data, or knowledge * Interactive… …   Wikipedia

  • Flow (psychology) — Flow is the mental state of operation in which the person is fully immersed in what he or she is doing by a feeling of energized focus, full involvement, and success in the process of the activity. Proposed by positive psychologist Mihály… …   Wikipedia

  • Visualization (computer graphics) — See also Visualization and Information graphics Visualization is any technique for creating images, diagrams, or animations to communicate a message. Visualization through visual imagery has been an effective way to communicate both abstract and… …   Wikipedia

  • Flow (computer networking) — In a Packet Switching network, a packet flow or traffic flow is a sequence of packets from one particular source (e.g. a computer host, process or class of service) to a single destination (another computer host, multicast group, broadcast domain …   Wikipedia

  • Scientific visualization — A scientific visualization of an extremely large simulation of a Rayleigh–Taylor instability caused by two mixing fluids.[1] Scientific visualization (also spelled scientific visualisation) is an interdisciplinary branch of science according to… …   Wikipedia

  • Data visualization — A data visualization of Wikipedia as part of the World Wide Web, demonstrating hyperlinks Data visualization is the study of the visual representation of data, meaning information that has been abstracted in some schematic form, including… …   Wikipedia

  • IBM History Flow tool — IBM s History Flow tool is a visualization tool for a time sequence of snapshots of a document in various stages of its creation. The tool supports tracking contributions to the article by different users, and can identify which parts of a… …   Wikipedia

  • Information visualization reference model — The Information visualization reference model is a reference model for information visualization, developed by Ed Chi in 1999. [Ed H. Chi. [http://www users.cs.umn.edu/ echi/phd/ A Framework for Information Visualization Spreadsheets] . Ph.D.… …   Wikipedia

  • Data flow diagram — example.[1] A data flow diagram (DFD) is a graphical representation of the flow of data through an information system, modelling its process aspects. Often they are a preliminary step used to create an overview of the system which can later be… …   Wikipedia

  • Traffic flow (computer networking) — For other uses, see Flow (disambiguation). In packet switching networks, traffic flow, packet flow or network flow is a sequence of packets from a source computer to a destination, which may be another host, a multicast group, or a broadcast… …   Wikipedia


We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.