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A mixer design for the pigtail braid

Binder, B J; Cox, Stephen M.


B J Binder

Stephen M. Cox


The stirring of a body of viscous fluid using multiple stirring rods is known to be particularly effective when the rods trace out a path corresponding to a nontrivial mathematical braid. The optimal braid is the so-called "pigtail braid", in which three stirring rods execute the usual "over-under" motion associated with braiding (plaiting) hair. We show how to achieve this optimal braiding motion straightforwardly: one stirring rod is driven in a figure-of-eight motion, while the other two rods are baffles, which rotate episodically about their common centre. We also explore the extent to which the physical baffles may be replaced by flow structures (such as periodic islands).


Binder, B. J., & Cox, S. M. (2008). A mixer design for the pigtail braid. Fluid Dynamics Research, 40(1), 34-44.

Journal Article Type Article
Acceptance Date Sep 14, 2006
Online Publication Date Mar 6, 2009
Publication Date 2008-01
Deposit Date Oct 23, 2007
Publicly Available Date Jan 31, 2008
Journal Fluid Dynamics Research
Print ISSN 0169-5983
Electronic ISSN 1873-7005
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 40
Issue 1
Pages 34-44
Keywords Chaotic advection, Braid, Stokes flow, Fluid mixing
Public URL
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