Europhys. Lett.
Volume 72, Number 5, December 2005
Page(s) 837 - 843
Section Interdisciplinary physics and related areas of science and technology
Published online 28 October 2005
Europhys. Lett., 72 (5), pp. 837-843 (2005)
DOI: 10.1209/epl/i2005-10301-2

Electroosmosis at inhomogeneous charged surfaces

Y. W. Kim and R. R. Netz

Physik Department, TU München - 85748 Garching, Germany

received 21 April 2005; accepted in final form 3 October 2005
published online 28 October 2005

The Helmholtz-Smoluchowski (HS) relation between the local electrostatic potential and lateral solvent velocity in a continuum fluid at a planar charged surface under the action of a tangential electric field is exact for smooth surfaces, even in the presence of ion correlations. At rough surfaces, the interplay of hydrodynamics and surface friction due to electrostatic and excluded-volume interactions between surface groups and counterions gives rise to pronounced deviations from HS-theory. This is demonstrated by hydrodynamic simulations of ions at charged corrugated surfaces. Derived effective electrokinetic surface charges are highly reduced, in agreement with the experimental trend.

82.45.-h - Electrochemistry and electrophoresis.
61.20.Qg - Structure of associated liquids: electrolytes, molten salts, etc.
47.15.Gf - Low-Reynolds-number (creeping) flows.

© EDP Sciences 2005