We study the dynamics of rod shaped particles in two-dimensional electromagnetically driven fluid flows. Two separate types of flows that exhibit chaotic mixing are compared: one with time-periodic flow and the other with constant forcing but nonperiodic flow. Video particle tracking is used to make accurate simultaneous measurements of the motion and orientation of rods along with the carrier fluid velocity field. These measurements allow a detailed comparison of the motion and orientation of rods with properties of the carrier flow. Measured rod rotation rates are in agreement with predictions for ellipsoidal particles based on the measured velocity gradients at the center of the rods. There is little dependence on length for the rods we studied (up to 53% of the length scale of the forcing). Rods are found to align weakly with the extensional direction of the strain-rate tensor. However, the alignment is much stronger with the direction of Lagrangian stretching defined by the eigenvectors of the Cauchy–Green deformation tensor. A simple model of the stretching process predicts the degree of alignment of rods with the stretching direction.
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April 2011
Research Article|
April 21 2011
Rotation and alignment of rods in two-dimensional chaotic flow
Shima Parsa;
Shima Parsa
1Department of Physics,
Wesleyan University
, Middletown, Connecticut 06459, USA
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Jeffrey S. Guasto;
Jeffrey S. Guasto
2Department of Physics,
Haverford College
, Haverford, Pennsylvania 19041, USA
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Monica Kishore;
Monica Kishore
2Department of Physics,
Haverford College
, Haverford, Pennsylvania 19041, USA
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Nicholas T. Ouellette;
Nicholas T. Ouellette
3Department of Mechanical Engineering and Materials Science,
Yale University
, New Haven, Connecticut 06520, USA
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J. P. Gollub;
J. P. Gollub
2Department of Physics,
Haverford College
, Haverford, Pennsylvania 19041, USA
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Greg A. Voth
Greg A. Voth
1Department of Physics,
Wesleyan University
, Middletown, Connecticut 06459, USA
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Physics of Fluids 23, 043302 (2011)
Article history
Received:
May 21 2010
Accepted:
March 04 2011
Citation
Shima Parsa, Jeffrey S. Guasto, Monica Kishore, Nicholas T. Ouellette, J. P. Gollub, Greg A. Voth; Rotation and alignment of rods in two-dimensional chaotic flow. Physics of Fluids 1 April 2011; 23 (4): 043302. https://doi.org/10.1063/1.3570526
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