Numerical study on the liquid phase structural evolution of high-temperature metal-oxide mixture in the magnetic field

In reactor safety analysis, the stratification phenomenon of the molten pool is crucial for the design of in-vessel retention techniques. During the course of the experimental study on the stratification of the molten pool using an electromagnetic cold crucible, the electromagnetic field affects the evolution of the structural morphology of the molten pool. This study constructs a multi-physics field model coupling electromagnetic field, flow field, temperature field, and two-phase flow to investigate the morphological structure, heat transfer, and fluid dynamics of immiscible two-phase liquids in the electromagnetic field. The model focuses on the effects of Lorentz force, buoyancy, surface tension, temperature gradients, and solidification on the two-phase liquid structure. The simulated result of the liquid-phases’ structure aligns well with experimental results. The computational results show that when subjected to an electromagnetic field, the metal surface undergoes a significant Lorentz force owing to the skin effect. Therefore, the metal was pushed towards the center of the molten pool. The buoyancy force causes the metal to reside above the molten pool. And under the combined effects of the Lorentz force and surface tension, the metal adopts a semi-spherical shape. In the absence of the Lorentz force, the buoyancy force predominates over the interaction forces between the two liquid phases, causing the metal to spread over the molten pool. In addition, natural convection due to temperature gradients affects the molten pool flow. During the solidification of the molten pool, the solidification of the oxide on the sidewalls restricts the flow and morphology of the metal. The study finds that the molten pool is primarily influenced by Lorentz force, followed by buoyancy force and natural convection, while surface tension has the least impact on the molten pool's morphology. These findings contribute to the understanding of the complex morphological evolution process of immiscible liquid phases with different conductivities in an electromagnetic field.