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Direct measurement of vorticity by optical probe

Published online by Cambridge University Press:  20 April 2006

Michael B. Frish
Affiliation:
School of Applied and Engineering Physics, Cornell University, Ithaca, N.Y. 14853
Watt W. Webb
Affiliation:
School of Applied and Engineering Physics, Cornell University, Ithaca, N.Y. 14853

Abstract

An optical method for the direct measurement of vorticity in liquid flows is described. At the present state of development it is capable of responding to vorticity fluctuations with a response time of about 1 msec and a spatial resolution of better than 50 μm. Small spherical particles suspended in the flow rotate with angular velocity accurately equal to half the local vorticity; thus measurements of the rotation rates of such particles indicate the vorticity. Transparent spherical particles of less than 50 μm diameter, each containing embedded planar crystal mirrors, have been developed for this purpose and are suspended in a refractive-index-matched liquid. Measurements of the times required for laser reflections from the mirrors to rotate through the small angle defined by a pair of slits yields the rotation rate, and thus the vorticity. Production and physical properties of the probe particles are reported. Theoretical capabilities and limitations of the method, including accuracy, spatial and temporal resolution, data rate, and background noise are calculated and found to be coupled to the optical geometry and flow field. Analysis yields procedures for selective optimization of each parameter as dictated by the particular application. Measurements of steady-state, laminar, two-dimensional Poiseuille flows demonstrate the effectiveness of the technique and confirm theoretical predictions.

Type
Research Article
Copyright
© 1981 Cambridge University Press

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References

Aref, H. & Siggia, E. D. 1980 Vortex dynamics of the two-dimensional turbulent shear layer. J. Fluid Mech. 100, 705.Google Scholar
Batchelor, G. K. 1967 An Introduction to Fluid Dynamics. Cambridge University Press.
Cadle, R. 1955 Particle Size Determination. Wiley-Interscience.
Chwang, A. & Wu, T. 1974 Hydromechanics of low-Reynolds-number flow. Part 1. Rotation of axisymmetric prolate bodies. J. Fluid Mech. 63, 607.Google Scholar
Eckelmann, H., Nychas, S. G., Brodkey, R. S. & Wallace, J. M. 1977 Vorticity and turbulence production in pattern recognized turbulent flow structure. Phys. Fluids 20, 5225.Google Scholar
Foss, J. F. 1977 The Vorcom, Part 2: Demonstration vorticity measurements. Third Annual Report, NASA, Langley Research Center.
Frenkiel, F. N., Klebanoff, P. S. & Huang, T. T. 1979 Grid turbulence in air and water. Phys. Fluids 22, 1606.Google Scholar
Hopff, H., Lüussi, H. & Gerspacher, P. 1964 Contribution to suspension polymerization. Makromolekulare Chemie 78, 24.Google Scholar
Jeffrey, J. B. 1922 The motion of ellipsoidal particles immersed in a viscous fluid. Proc. Roy. Soc. A 102, 161.Google Scholar
Johnson, D. H. & Webb, W. W. 1972 Bull. Am. Phys. Soc. 17, 1084. See also Johnson, D. H. 1975 Measurement of the rate of strain tensor in a turbulent flow using light scattering from asymmetric particles. Ph.D. thesis, Cornell University.
Kovasznay, L. S. G. 1978 Large scale structure in turbulence: A question or an answer? In Structure and Mechanisms of Turbulence I (ed. H. Fiedler). Lecture Notes in Physics, vol. 75. Springer.
Landau, L. & Lifshitz, E. 1959 Fluid Mechanics. Pergamon.
Lindgren, B. W. 1976 Statistical Theory, $ 3.2. MacMillan.
Redfarn & Bedford 1960 Experimental Plastics: A Practical Course for Students. Wiley-Interscience.
Rodriguez, F. 1970 Principles of Polymer Systems. McGraw-Hill.
Roshko, A. A. 1976 Structure of turbulent shear flows: A new look. A.I.A.A. J. 14, 1349.Google Scholar
Tennekes, H. & Lumley, J. 1972 A First Course in Turbulence. Massachusetts Institute of Technology Press.
Willmarth, W. W. & Bogar, T. J. 1977 Survey and new measurements of turbulent structure near the wall. Phys. Fluids 20, 59.Google Scholar

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