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Phys. Rev. Lett. 88, 254501 (2002) [4 pages]

Experimental Measurements of Stretching Fields in Fluid Mixing

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Greg A. Voth1, G. Haller2, and J. P. Gollub1,3,*
1Department of Physics, Haverford College, Haverford, Pennsylvania 19041
2Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
3Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania 19104

Received 30 November 2001; published 6 June 2002

Using precision measurements of tracer particle trajectories in a two-dimensional fluid flow producing chaotic mixing, we directly measure the time-dependent stretching field. This quantity, previously available only numerically, attains local maxima along lines that coincide with the stable and unstable manifolds of hyperbolic fixed points of Poincaré maps. Contours of a passive impurity field are found at each instant to be oriented parallel to the lines that have recently experienced large stretching. The local stretching varies by 12 orders of magnitude.

© 2002 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.88.254501
DOI:
10.1103/PhysRevLett.88.254501
PACS:
47.52.+j, 05.45.-a, 47.20.Ky

*Email address: jgollub@haverford.edu.

 
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