Multi-point optical measurements of simultaneous vectors in unsteady flow-a review

R. J. Adrian

Research output: Contribution to journalArticlepeer-review

237 Scopus citations


Optical techniques for measuring large numbers of simultaneous velocity vectors in two- and three-dimensional regions of fluid flows are reviewed. These nonobtrusive methods provide spatial information of the type that is available from flow visualization with accuracy approaching that of single-point methods such as laser Doppler velocimetry and hot wire. The principle underlying each technique is the measurement of the simultaneous displacemen of images of many marked fluid particles. Many methods are available. These include streak photography; marker image tracking methods using photography, cinematography, holography, and video recording; line tracking methods using hydrogen bubbles and photochromic tracers; and fluorescent particle tracing. Pulsed laser methods, specifically laser speckle velocimetry and particle image velocimetry, provide high spatial resolution and good accuracy.

Original languageEnglish (US)
Pages (from-to)127-145
Number of pages19
JournalInternational Journal of Heat and Fluid Flow
Issue number2
StatePublished - Jun 1986
Externally publishedYes


  • optical techniques
  • turbulent flow
  • unsteady flow
  • velocity measurement

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


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