2-D and 3-D Electroconvection, Experiments and Models.

Abstract

In recent years, a lot of work has been devoted to electrochemical growth without supporting electrolyte1. A model, proposed by one of us2, predicts the existence of a positive space charge and of a large electric field in the active zones of the deposit. This leads to the existence of a coulombic force on the liquid. We show that this coulombic force triggers convective vortices in Hele-Shaw cells3,4, while it triggers vortex rings in three-dimensional cells5.We then couple the electrochemical process to the convective flow and show that, while the border between the depleted and concentrated zones has the shape of an arch in Hele-Shaw cells, it has a toroidal shape in 3-D. When many vortex rings are present, the border between the depleted and the concentrated solution is in the form of domes. We give experimental evidence of the vortex rings. (The original presentation was accompanied by a video movie which can be obtained upon request).