Electrically induced flows in the vicinity of a dielectric stripe on a conducting planeF. Nadal1, F. Argoul1, P. Kestener1, B. Pouligny1, C. Ybert1 and A. Ajdari2
1 Centre de Recherche Paul Pascal, Avenue Schweitzer, 33600 Pessac, France
2 Laboratoire de Physico-Chimie Théorique, UMR CNRS 7083, ESPCI, 10 rue Vauquelin, 75005 Paris, France
(Received 20 June 2002 / Published online: 30 January 2003)
We report a theoretical and experimental study of the hydrodynamic flow induced by an a.c. electric field in the vicinity of a dielectric stripe deposited on a conducting plate. In the theoretical part, we model the stripe as a small change of the surface capacitance of the plate, and a perturbative approach is used to perform the calculations. This approach predicts an outwards rectified electro-osmotic slip along the surface that generates two steady counter-rotating rolls, the size of which decreases with the frequency. In the experimental section, we use tracers to determine the structure of the flow and investigate its dependence on the frequency and the amplitude of the applied voltage. The structure and amplitude of the observed flow compares satisfactorily with the theoretical analysis. This could guide the design of surface-controlled flows and help to understand the collective behavior of colloids near electrodes.
82.70.Dd - Colloids.
47.65.+a - Magnetohydrodynamics and electrohydrodynamics.
85.90.+h - Other topics in electronic and magnetic devices and microelectronics.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002