SOLIDIFICATION EXPERIMENTS AND MAGNETOHYDRODYNAMIC MODELS IN ELECTROMAGNETIC LEVITATION

Electromagnetic levitation (EML) is a technique for containerless processing. The unique environment of containerless processing allows for the study of highly reactive melts at elevated temperatures. In containerless processing, the interface between a melt and its container is removed, reducing chemical contamination. In addition, levitation techniques reduce the available heterogeneous nucleation sites, providing greater access to the undercooled region for solidification studies. Levitation techniques provide the environment to study the fundamental behavior and thermophysical properties of liquid metals. During electromagnetic levitation experiments, magnetohydrodynamic flow is driven in the sample by the electromagnetic force field. This flow can have various effects on the sample, some of which are detrimental to measurements. In other experiments the internal flow is an experimental variable that is necessary to interpret the experimental results. However, the flow in most metallic melts is difficult to directly measure because metallic melts are opaque and featureless, while also quickly dissolving any tracer particles. Since the flow in the sample is not possible to measure directly from the experimental observations, computational fluid dynamics (CFD) is used to calculate the flow using the experimental conditions present at the point of interest for a given experiment. The work presented here contributes to the steady-state models used to calculate the flow resulting from the EML force field. The current model presented here is validated both against an experimental case and against previous published models. During development of the new models, variations across different versions of ANSYS Fluent were observed. The differences were explored and found to be within an acceptable range. The steady-state model was applied to a series of parabolic flight experiments on Fe-10wt\%Si. Additionally, the steady-state model was used to calculate the flow conditions on a zirconium sample at the time of anomalous solidification events observed during ISS-EML experiments. The steady-state model was expanded to a transeint model to further explore the flow effects on the sample. By developing a transient model, the effects of the excitation pulse on the internal flow was calculated for a $Zr_{64}Ni_{36}$ sample. This sample was observed to experience pulse-triggered solidification. The transient model provided insights into behavior of the internal flow at the time of solidification