Solid-liquid phase change subjected to unipolar charge injection from a circular wire electrode

Abstract

A numerical investigation of isothermal melting of a dielectric phase change material in a square cavity subjected to unipolar charge injection from a circular wire electrode is reported. Governing equations for the solid-liquid phase change under the influence of an electric field include the Navier–Stokes equations for fluid flow, energy equation for thermal transport, Poisson equation for electric potential, and the Nernst-Planck equation for charge conservation. An enthalpy source-term based fixed grid approach is adopted to model the melting process. The governing equations that consider the coupled interactions between flow, thermal and electric fields are solved using the finite volume framework of OpenFOAM®. Time evolution of the melting rate, maximum flow velocity, mean Nusselt number, and mean Coulomb force in the electrohydrodynamic flow assisted melting process is mapped. The mechanism and role of electrohydrodynamic forces on influencing the net flow and melt interface morphology is studied. The competing viscous, buoyancy, and electric forces result in an altered flow pattern that aids the melting process. The enhancement in the rate of melting at different strengths of buoyancy and electrostatic forces is quantified. Furthermore, the effects of the radius of the circular wire electrode in relation to the cavity size are highlighted. A maximum of 63% enhancement in melting rate is observed within the considered parameter space.