Dynamic simulation of an electrorheological fluid

Journal Article · Fri Jan 31 23:00:00 EST 1992 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.462070· OSTI ID:5082889

Bonnecaze, R T; Brady, J F ^[1]

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1. Department of Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States)

A molecular-dynamics-like method is presented for the simulation of a suspension of dielectric particles in a nonconductive solvent forming an electrorheological fluid. The method accurately accounts for both hydrodynamic and electrostatic interparticle interactions from dilute volume fractions to closest packing for simultaneous shear and electric fields. The hydrodynamic interactions and rheology are determined with the Stokesian dynamics methodology, while the electrostatic interactions, in particular, the conservative electrostatic interparticle forces, are determined from the electrostatic energy of the suspension. The energy of the suspension is computed from the induced particle dipoles by a method previously developed (R. T. Bonnecaze and J. F. Brady, Proc. R. Soc. London, Ser. A {bold 430}, 285 (1990)). Using the simulation, the dynamics can be directly correlated to the observed macroscopic rheology of the suspension for a range of the so-called Mason number, {ital Ma}, the ratio of viscous to electrostatic forces. The simulation is specifically applied to a monolayer of spherical particles of areal fraction 0.4 with a particle-to-fluid dielectric constant ratio of 4 for {ital Ma}=10{sup {minus}4} to {infinity}. The effective viscosity of the suspension increases as {ital Ma}{sup {minus}1} or with the square of the electric field for small {ital Ma} and has a plateau value at large {ital Ma}, as is observed experimentally. This rheological behavior can be interpreted as Bingham plastic-like with a dynamic yield stress. The first normal stress difference is negative, and its magnitude increases as {ital Ma}{sup {minus}1} at small {ital Ma} with a large {ital Ma} plateau value of zero. In addition to the time averages of the rheology, the time traces of the viscosities are presented along with selected snapshots'' of the suspension microstructure.

• OSTI ID: 5082889
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 96:3; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

661300* -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CALCULATION METHODS
DIELECTRIC MATERIALS
DISPERSIONS
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATORS
ELECTROSTATICS
EQUIPMENT
FLUID MECHANICS
HYDRODYNAMICS
MATERIALS
MECHANICS
PARTICLES
RHEOLOGY
SIMULATION
SOLVENTS
SUSPENSIONS