Phase Change in a Three-Dimensional Rectangular Cavity Under Electromagnetically Simulated Low Gravity: Top Wall Heating With an Unfixed Material

Abstract

ABSTRACT In this article, melting of an unfixed phase-change material (PCM), gallium, in a simulated low-gravity environment via an electromagnetic field has been modeled numerically in a three-dimensional enclosure. Both transverse electric and magnetic fields are used to generate a Lorentz force, which opposes the influence of gravity. This Lorentz force acts to damp and/or counteract the convective flow induced by the floatation of the solid PCM within the melt, thereby simulating the low-gravity environment of outer space. The problem is formulated as one-domain by employing an enthalpy-based transformation of the energy equation, which allows for one set of governing equations to be solved. The governing equations are then discretized using a control-volume-based finite-difference scheme. The results show that key melting characteristics found under a true low-gravity environment can be simulated by both the application of a magnetic field alone or by the application of an electromagnetic filed. Each case of simulated low gravity has distinct advantages and disadvantages, such that the preferred method of simulation will depend on which characteristics are of more importance. The magnetic-only case allows for lower levels of gravity to be obtained. However, there is a significant distortion of the flow field and a resultant effect of the transient region of the solid velocity. The electromagnetic case allows for more accurate representation of the transient solid velocity, but there is a sacrifice in the level of low gravity achievable.