Electrically driven flows and instabilities in liquid metal batteries

Liquid metal batteries are currently discussed as a means to economic large scale energy storage. They consist of three fluid layers in stable density stratification. This fully liquid arrangement relies on the stable stratification to remain intact in order to function properly. Fluid motion has the potential to disrupt the molten salt layer sandwiched in-between the upper and lower metal electrodes. A situation like this would result in an internal short-circuit and thus in a malfunction of the cell. We consider here two electromagnetic flow driving mechanisms: the Tayler instability and rotational Lorentz force distributions leading to electro-vortex flows. In a simplified setting, the stabilization of the electrolyte layer can be described fairly well by the ratio of potential to kinetic energy, i.e., the Richardson number.