Effects of finite conductivity in electrorheological fluids
Electrorheological (ER) effects arise from electrostatic forces between particles suspended in a carrier fluid, induced when an electric field is applied. These forces are a consequence of field distortion in the neighborhood of each particle. Although it is known that finite conductivity can influence ER effects, the standard assumption has been that the contrast between the dielectric constants of particles and surrounding fluid is responsible for the field distortion. This is likely to be seriously in error with a low-frequency or dc applied field if measurable conductivity is preset in either the particles or fluid. Below a crossover frequency, f{sub c}, field distortion becomes dominated by conductivities, and a variety of other complications may arise. Conductive particles could acquire a net charge and fail to participate in chain formation, and a relatively high fluid conductivity may lead to competing processes, including the possibility of a significant distortion of the field distribution in an ER cell. The latter phenomenon is not directly related to f{sub c} and might occur at frequencies above it. Any of these effects could lead to field dependent or frequency dependent behavior of experimental results. 7 refs., 5 figs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5990163
- Report Number(s):
- SAND-91-1409C; CONF-9110290--1; ON: DE92002987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHARGED PARTICLES
DIELECTRIC PROPERTIES
DIPOLES
DISPERSIONS
ELECTRIC CONDUCTIVITY
ELECTRIC FIELDS
ELECTRICAL PROPERTIES
ELECTROSTATICS
FLUID MECHANICS
IONS
MECHANICS
MULTIPOLES
PHYSICAL PROPERTIES
RHEOLOGY
SUSPENSIONS