Paper Number
AM2 

Session
Active, Motile, and Field Responsive Materials

Title
The dynamics of magnetic oblate spheroids under a rotating magnetic field

Presentation Date and Time
October 10, 2017 (Tuesday) 10:15

Track / Room
Track 1 / Crystal A

Authors (Click on name to view author profile)

1. Tan, Mingyang (Oregon State University, CBEE)
2. Walker, Travis W. (Oregon State University, CBEE)

Author and Affiliation Lines (in printed abstract book)
Mingyang Tan and Travis W. Walker
CBEE, Oregon State University, Corvallis, OR 97331

Speaker / Presenter 
Tan, Mingyang

Text of Abstract
Anisotropic microstructures are commonly found in natural materials, endowing the materials with enhanced properties in certain orientations, including the prospect of self-shaping characteristics. Synthetic composites with anisotropic properties can be achieved by embedding aspherical particles inside a polymer matrix and by later using an external field (e.g., electric, magnetic, and optical field) to align the particles into a certain orientation. One- or two-dimensional anisotropy can be performed based on the geometry of the particles and the properties of the external field. In this study, aligning magnetic oblate spheroids via a rotating uniform magnetic field creates a two-dimensional anisotropic material. The particles undergo a rotational motion, induced by the external field, and a translational motion, induced by the dipole-dipole interaction between particles. We simulate the dynamics of the particles’ motion in the Stokes flow region as a result of the trivial Reynolds number of this system. To obtain the realistic dynamics of this phenomenon, the hydrodynamic interactions are included by using Stokesian dynamics. While short-range interactions between two oblate spheroids are intractable to obtain, we use a pseudo-disk model, where spheres are packed into a disk shape, to simulate the spheroid-spheroid hydrodynamic interaction. At equilibrium, a hexagonal grid of particles form aligned sheets that are separated along the direction perpendicular to the sheets. The separating distance depends on the volume fraction of the particles.