Aug 26, 2005 - The black neon tetra (Fig. 1) of body length 3.6 cm maintains a steady position by flicking its fins and creating vortices. The fish's breathing is ...
Visualization of a fish wake using tobacco mosaic virus David L. Hu, Lucy Mendel, Brian Chan, Thomas Goreau, and John W. Bush Citation: Phys. Fluids 17, 091103 (2005); doi: 10.1063/1.1942515 View online: http://dx.doi.org/10.1063/1.1942515 View Table of Contents: http://pof.aip.org/resource/1/PHFLE6/v17/i9 Published by the AIP Publishing LLC.
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PHYSICS OF FLUIDS 17, 091103 共2005兲
FIG. 1.
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FIG. 2.
Visualization of a fish wake using tobacco mosaic virus David L. Hu, Lucy Mendel, and Brian Chan Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
Thomas Goreau Global Coral Reef Alliance, Cambridge, Massachusetts 02139
John W. M. Bush Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 共Received 15 March 2005; published online 26 August 2005兲 关DOI: 10.1063/1.1942515兴
We have redeveloped a flow visualization technique pioneered by Fritz Goro,1 Time–Life science photographer from 1937–1978, but never described in print. Linearly polarized light is transmitted through a dilute aqueous suspension of tobacco mosaic virus2 共TMV兲 and viewed through a crossed polarizer. Flow disturbances cause the rod-shaped TMV to orient along flow lines and so differentially refract incoming light to produce bright spots in regions of strong shear. The
1070-6631/2005/17共9兲/091103/1/$22.50
viral solution is invisible to the naked eye and only becomes apparent under examination through a polarizer. An attractive feature of this technique is that it is harmless to fish, providing a safe alternative for visualizing their wakes. The black neon tetra 共Fig. 1兲 of body length 3.6 cm maintains a steady position by flicking its fins and creating vortices. The fish’s breathing is marked by a glowing white region created by the suction into its mouth. In Fig. 2, the fish swims upward generating a conical wake whose breadth and turbulent interior is made evident by the TMV. The fish brakes by extending its pectoral fins and blowing a vortex ring from its mouth. Polarized light can also be used to illuminate a sufficiently low dilution of Kalliroscope 共Fig. 3兲 that it is invisible to the naked eye and benign to fish. 1
2
T. Goreau, P. Goreau, and S. Goreau, On the Nature of Things: The Scientific Photography of Fritz Goro 共Aperture, New York, 1993兲. F. C. Bawden, N. W. Pirie, J. D. Bernal, and I. Fankuchen, “Liquid crystalline substances from virus-infected plants,” Nature 共London兲 38, 1051 共1936兲.
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© 2005 American Institute of Physics
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