Analysis and simulation of the thermal and viscous model of the melt spinning process

Abstract

The Melt Spinning process is used for the manufacture of thin ribbons of amorphous materials. The material is injected through a nozzle in the liquid state and solidifies upon contact with a rotating wheel. In this work, we intend to find a computerized simulation of OpenFOAM® with a thermal profile of the material from its ejection through the nozzle to the conformation of the tape itself. A two-phase model of the "Volume of Fluids" (VOF) type is used. Although neither of the two fluids (molten metal and air) can be considered compressible for the working pressures, a compressible nature resolver is used. This allows to represent the changes of density in the air by temperature changes and to define a thermo-physical model for the alloy, not available in resolvers of incompressible nature. For this, it is considered an alloy of constant thermal conductivity, specific heat and density. The phase change is represented by a model that relates viscosity (μ) to temperature (𝑇) in which the viscosity increases several orders of magnitude when the material passes below the crystallization temperature. Among the options of viscous models offered by OpenFOAM®, a polynomial model whose coefficients were determined after expanding the relation μ = -𝑎 (𝑇 -𝑇 *) 7 + μ * is selected. Using OCTAVE, the values ​​of the coefficient 𝑎, 𝑇 * and μ * were modified until an adjustment curve [1] was obtained with the expansion of the function to obtain the final coefficients of the polynomial within the temperature range of 600 to 1700ºC