Volume 77, Number 1, January 2007
Article Number 18002
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 29 December 2006
EPL, 77 (2007) 18002
DOI: 10.1209/0295-5075/77/18002

MR fluid structure in quasi-2D

R. Haghgooie and P. S. Doyle

Massachusetts Institute of Technology - 77 Massachusetts Ave., Room 66-456 Cambridge, MA 02139, USA

received 24 July 2006; accepted in final form 7 November 2006; published January 2007
published online 29 December 2006

We study the effects of quasi-two-dimensional (quasi-2D) confinement on the self-assembly of super paramagnetic colloids found in magnetorheological (MR) fluids using the Brownian dynamics simulation technique. A uniform external magnetic field is directed normal to a thin-slit in which dilute MR fluid is confined. The thickness of the confining slit ranges from a single colloid diameter to several colloid diameters. The steady-state structure that forms under such extreme confinement is shown to depend heavily upon the thickness of the slit. As the slit-thickness is increased from one colloid diameter (2D confinement) the structure of the dilute MR fluid changes non-monotonically. We introduce a ground-state model to predict the structure as a function of the slit-thickness and the volume fraction of the fluid. The model is able to quantitatively predict the structures observed in our simulations.

82.70.Dd - Colloids .
68.03.Hj - Structure: measurements and simulations .
75.40.Mg - Magnetic properties and materials: Numerical simulation studies .

© Europhysics Letters Association 2007