Open Access

ARTICLE

Comparison of EHD-Driven Instability of Thick and Thin Liquid Films by a Transverse Electric Field

Payam Sharifi¹, Asghar Esmaeeli²

1 Department of Mechanical Engineering and Energy Processes Southern Illinois University Carbondale, Illinois 62901. Email: psharifi@siu.edu
2 Department of Mechanical Engineering and Energy Processes Southern Illinois University Carbondale, Illinois 62901. Email: esmaeeli@engr.siu.edu

Fluid Dynamics & Materials Processing 2013, 9(4), 389-418. https://doi.org/10.3970/fdmp.2013.009.389

Abstract

This study aims to explore the effect of liquid film thickness on the electrohydrodynamic-driven instability of the interface separating two horizontal immiscible liquid layers. The fluids are confined between two electrodes and the light and less conducting liquid is overlaid on the heavy and more conducting one. Direct Numerical Simulations (DNSs) are performed using a front tracking/finite difference scheme in conjunction with Taylor-Melcher leaky dielectric model. For the range of physical parameters used here, it is shown that for a moderately thick lower liquid layer, the interface instability leads to formation of several liquid columns and as a result of competition between these columns eventually a big column is formed. On the other hand, for a thin lower layer the lower electrode strongly influences the growth of the instability, leading to a short and a longer column that are connected together by a thin liquid film. When the film becomes too thick, more columns are formed, but the fluid system does not reach a steady state because the liquid columns grow so rapidly that they hit the top electrode. The flow structure is examined and the variation of the steady state kinetic energy of the system with the film thickness and the applied electric voltage is explored.

---