On the geometrical shape of self-organizing electro-hydrodynamic convective flows generated in thin-layer electrolytic cells

Abstract

A low-voltage thin-layer electrolysis of solutions of low conductivity can generate electric forces which cause the convective flow of the fluid. This electrohydrodynamic convection exhibits self-organization in such a way that cooperating convective flows form elongated or cellular structures similar to those observed for thermal convection. These structures are easily observable as patterns of luminescence if the electrolyzed substance is rubrene, the ionic radicals of which recombine with the emission of a visible light from the places determined by the geometrical shape of convective flows. Following previous experimental and theoretical studies, in the present paper the geometrical distributions of luminescence for linear and cellular patterns are analyzed in terms of theoretical calculations for the two-dimensional layer of the fluid. In particular, the structure of flows forming single convective hexagonal cells in a three-dimensional space is proposed. Numerical results and theoretical predictions are compared with experimental observations.