Computer simulations of nonequilibrium structure formation in electrorheological fluids.

Abstract

The temporal evolution of three-dimensional structure in an electrorheological fluid under nonequilibrium, high-field conditions is examined by a computer-simulation method similar to that of Klingenberg, van Swol, and Zukoski [J. Chem. Phys. 91, 7888 (1989)]. A variety of characteristic real-space properties (e.g., the radial distribution function) and the static structure factor S(q) are monitored during the simulation. The field-induced polarization of particles causes rapid chain formation followed by a kinetic trapping into a complicated gel-like state with no obvious lateral ordering. For all volume fractions considered, the first percolating chain appears at ten times the average time to first contact. Quenching of the gel is nearly complete on an order of magnitude longer time scale. The formation of chains results in the growth and narrowing of Bragg-like peaks in S(q) along the field direction. In the direction perpendicular to the field, the first peak in S(q) also grows and shifts to smaller q.