Liquid bulk rotation induced by electric field at free surface

In this paper, we induce rotation in a bulk of polar liquid with one free surface, by applying external crossed electric fields. We show that the induced rotation is due to the imposed stresses at the free surface of the liquid. A simple theoretical model was developed based on solving the Navier-Stokes equation that enables us to calculate the average induced stress in the liquid bulk, using experimental measurements of the angular velocity of the liquid. Our results indicate that the induced stresses and the angular velocities of the rotating liquid are independent from the electrical conductivity of the liquid. However, the induced stresses linearly depend on the external electric field and the applied electric voltage for passing the electric current through the bulk. Both experimental results and the theoretical model show that the angular velocity, linearly changes with depth. © 2015 AIP Publishing LLC.