Electroosmosis at inhomogeneous charged surfacesY. 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