Role of convection in thin-layer electrodeposition

Measurements of fluid motion during thin-layer electrochemical growth reveal that convection arising from concentration gradients that are transverse to gravity is immediate and substantial for experimental conditions typical to many studies in the literature. A particle tracking technique is used to determine and follow the time evolution of the convective velocity field. The contribution of buoyancy driven convection to local and global transport is compared to that arising from diffusion. A transition is observed from a regime in which the convection rolls near each electrode grow as t^4/5 to a regime with the roll size growing as t^1/2. Convection generated by electric fields can also be important in electrodeposition experiments; the measured electroconvective velocities are found to be much smaller than those predicted by the theory of Fleury and Chazalviel.