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Glass transition was primarily considered to be not phase transition; instead, regarded as pseudo secondorder phase transition due to its similarity to the ordinary second-order phase transition. Recent single-molecule spectroscopy developments have prompted re-investigating glass transition at the microscopic scale, confirming that the initial classification is correct and revealing that glass transition includes phenomena similar to second-order phase transition. They are characterized by microscopic collective polymer motion and discontinuous changes in temperature dependent relaxation times within a temperature window that includes the polymer calorimetric glass transition temperature. Generally, atom or molecule collective motion and discontinuous changes in physical quantities including relaxation times characterize critical phenomena associated with second-order phase transitions near specific temperatures. Thus, second-order phase transition phenomena are involved in polymer glass transition.

The main goal of this work is to prove the reliability of the Volume of Fluid (VOF) model for a top-submerged-lance (TSL) gas injection in a liquid metal bath, therefore trying to close the gap between the modelling of common air/water lab setups and real TSL slag-bath furnaces. Suitable validation data were provided by HZDR, where X-ray imaging was applied to picture the multiphase flow in an Argon - Ga77.2In14.4Sn8.4 system [1].

We report laboratory experiments focusing on bubbling phenomena arising from gas injection through a top submerged lance (TSL) in a liquid metal layer. Visualization was performed in the eutectic alloy GaInSn using X-ray radiography. Argon bubbles were injected through the nozzle positioned at three different submergence depths. The spatial distribution of time averaged void fraction was obtained by image processing for two-dimensional projected images. The results show that the deep position of the submerged lance causes an asymmetric large-scale circulation inside the fluid vessel. Bubbling frequencies were calculated by fast Fourier Transformation from fluctuations of the image brightness in the vicinity of the nozzle injection point. The frequency is not changed for variations of the gas flow rate and the submergence depth of the nozzle. An increasing gas flow rate results in an increasing size of the gas bubbles and mean bubble velocities.

Large-scale, coherent flow structures of Rayleigh-Bénard convection in a finite liquid metal layer were examined experimentally by means of ultrasonic Doppler velocimetry. The fluid layer with aspect ratio of five and L = 40 mm in height was filled with eutectic alloy of GaInSn (Prandtl number, Pr = 0.03), and multiple ultrasonic transducers for the velocimetry were mounted in the side wall of the vessel to capture three-dimensional structures of the convection. Spatio-tempral velocity maps obtained at different Rayleigh numbers in the range, 7900 < Ra < 180000, elucidated emergences of wavy-roll-like coherent structures, where the roll axis is determined quasi-randomly. The roll structure takes transition with reducing the number of rolls from four to three as Ra increases via intermediate regime between the two conditions, four or three rolls. With further increase of Ra a cellular structure with characteristics of fully developed thermal turbulence occupies the entire fluid layer. We will discuss details on derivation of the power law and relation with turbulent superstructures that have recently been discussed.

We report on laboratory experiments focusing on bubbling phenomena arising from gas injection through a top submerged lance (TSL) in a liquid metal layer. Visualization was performed in the eutectic alloy GaInSn using X-ray radiography. Argon bubbles were injected through the nozzle positioned at three different submergence depths. Essential parameters such as the bubble size, bubble shape, detachment frequency or the two-dimensional gas distribution in the flat vessel were obtained by image processing. The results show that the deep position of the submerged lance causes an asymmetric large-scale circulation inside the fluid vessel. Bubble detachment frequencies were calculated by Fast Fourier Transformation from fluctuations of the image intensity in the vicinity of the nozzle injection point. This frequency does not show strong variations with respect to changes of the gas flow rate and the submergence depth of the nozzle. An increasing gas flow rate results in an increasing two-dimensional projected bubble area and the occurrence of a significant number of small bubbles being trapped by the strong fluid flow in the liquid metal layer.

The present paper focuses on the application of CFD techniques to investigate the Top-Submerged-Lance (TSL) gas injection in liquid metal. Previous works of the authors have shown that up- and down-scaling procedures based on the modi-fied Froude number have some shortcomings, as this approach does not take into account the interfa-cial and viscous forces. Indeed surface tension and dynamic viscosity of the smelting slags (σ = 0.4-0.5 N/m, μ = 0.2 Pa·s) are higher than the operating fluids that have been used in literature (water, par-affin oil), which have been used to study TSL injection in down-scaled furnaces.. In order to get closer to real systems, the authors study the TSL injection of Argon in a liquid metal. An experimental campaign was carried out at the Magnetohydrodynamic Department of Helmholtz-Zentrum Dresden-Rossendorf (HZDR), where the eutectic alloy GaInSn was used as liquid phase. The alloy is liquid at room temperature, and X-Ray imaging is used to picture the multiphase flow in a qua-si-2D vessel (140x140x12 mm). The aim of the present work is to demonstrate the applicability of CFD techniques to model multi-phase flows involving liquid metals, and validate the model using the data produced at HZDR. The commercial software ANSYS Fluent® was used together with the Volume of Fluid model to directly resolve the gas-liquid interphase. Some features of the flow, such as the void fraction distribution and bubble detachment frequency are tracked with CFD and compared to the experimental data. The ef-fect on the hydrodynamics of different operating conditions, such as the lance immersion depth is investigated. The authors are currently extending the work to new geometries and operating conditions, in order to get a broader amount of data, useful for the validation of models and for the further understanding of the TSL injection.

Large-scale circulations of Rayleigh-Bénard convection in a finite liquid metal layer were examined experimentally by means of ultrasonic Doppler velocimetry. The fluid layer with aspect ratio of five and L = 40 mm in height was filled with eutectic alloy of GaInSn (Prandtl number, Pr = 0.03), and multiple ultrasonic transducers for the velocimetry were mounted in the side wall of the vessel to capture 3D structures of the convection.