Transient electrophoresis of a dielectric sphere
Date Issued
2005
Date
2005
Author(s)
Huang, You-Ching
DOI
en-US
Abstract
A theoretical study is presented for the dynamic electrophoretic response of a charged spherical particle in an unbounded electrolyte solution to a step change in the applied electric field. The electric double layer surrounding the particle may have an arbitrary thickness relative to the particle radius. The transient Stokes equations modified with the electrostatic effect which govern the fluid velocity field is linearized by assuming that the system is only slightly distorted from equilibrium. Semi-analytical results for the transient electrophoretic mobility of the particle are obtained as a function of relevant parameters by using the Debye-Huckel approximation. The results demonstrate that the electrophoretic mobility of a particle with a constant density at a specified dimensionless time normalized by its steady-state quantity decreases monotonically with a decrease in the parameter , where is the Debye screening length and a is the particle radius. For a given value of , a heavier particle lags behind a lighter one in the development of the electrophoretic mobility. In the limits of and , our results reduce to the corresponding analytical solutions available in the section 2.2 and 2.3. The electrophoretic acceleration of the particle is a monotonic decreasing function of the time for any fixed value of . In practical applications, the effect of the relaxation time for transient electrophoresis is negligible, regardless of the value of or the relative density of the particle.
Subjects
暫態
電泳
Transient
electrophoresis
Type
thesis
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