NUMERICAL SIMULATION OF THE LIQUID EXTRACTION FROM A STRATIFIED LIQUID-VAPOR ZONE USING ELECTROHYDRODYNAMIC EFFECTS

A quasi-steady numerical methodology was developed to predict the liquid extraction from a stratified liquid-vapor zone due to electrohydrodynamics (EHD). The stratified liquid-vapor was in a tube, and a step DC voltage was applied using a central electrode along the tube axis. The solution for the electric field was coupled with the Navier-Stokes equations to determine the interfacial velocities. Here, the electric field imposes an interfacial force on the liquid interface, which was estimated using the equation developed by Stratton [1941] assuming a free charge interface. The electric field and the momentum equations were solved iteratively for small time steps, using the interfacial force due to the electric fields as the boundary condition at the liquid interface for solving for the velocity in the liquid phase. The position of the liquid interface for each iteration was updated using the interfacial velocity from the previous iteration. The numerical simulations were performed using a commercial finite element code. The liquid extraction times were estimated, and were found to be in good agreement with those estimated from flow visualization experiments.