Numerical representations for flow velocity and shear rate inside electromagnetically levitated droplets in...

Area of Science:

• Materials Science
• Fluid Dynamics
• Electromagnetism

Background:

• Containerless processing using electromagnetic levitation (EML) in microgravity enables materials research.
• Advective flow in levitated molten alloys significantly impacts solidification and thermophysical property measurements.
• Accurate prediction of flow velocity is essential for optimizing melt processing conditions.

Purpose of the Study:

• To develop a predictive model for flow velocity and shear rate in electromagnetically levitated molten alloys.
• To establish a functional relationship between flow characteristics and processing parameters (heating voltage, material properties).
• To analyze the influence of internal advection on the transition from laminar to turbulent flow.

Main Methods:

• Application of a magnetohydrodynamic (MHD) model to electromagnetically levitated droplets.
• Development of a polynomial function to represent maximum flow velocity and shear rate.
• Parametric study across a range of operational conditions and material properties.

Main Results:

• Maximum flow velocity and shear rate are expressed as polynomial functions of heating voltage, density, viscosity, and electrical conductivity.
• Internal advection in Fe-19Cr-21Ni steel is shown to be temperature-dependent and influences laminar-turbulent transition.
• The model provides predictions applicable to various alloys like Ni-based superalloys and Ti-6Al-4V.

Conclusions:

• The developed MHD model effectively predicts flow behavior in EML processed alloys.
• Understanding advection is critical for controlling solidification and accurately measuring properties of levitated materials.
• The findings support optimized processing of commercially important metallic alloys.