Y. Hu et al., OBSERVATION AND SIMULATION OF ELECTROHYDRODYNAMIC INSTABILITIES IN AQUEOUS COLLOIDAL SUSPENSIONS, The Journal of chemical physics, 100(6), 1994, pp. 4674-4682
When an alternating linear electric field is applied to an aqueous sus
pension of micron-size polystyrene particles, hydrodynamic instabiliti
es are seen at a frequency range between 2 and 200 kHz. The formation
of elongated bands of particles oriented at certain angles relative to
the direction of the applied electric field and circulation of partic
les within the bands are observed. We examine the phase lag between th
e induced dipole moments of the particles and the effects of this on t
he interactions between neighboring particles. Because the phase lag c
auses neighboring particles to exert torques upon one another, thereby
causing spinning of double layers, we propose a phenomenological mode
l in which there is a symmetry breaking between the direction of the p
olarization of the particles and the direction of the applied electric
field. Based on this modified dipole-dipole interaction, and together
with hydrodynamic interactions, we are able to simulate the formation
of the tilted bands of particles. The sense of circulation of particl
es within a band also agrees with our experimental observations.