Beckwith, Christopher, Djambazov, Georgi ORCID: 0000-0001-8812-1269 , Pericleous, Koulis ORCID: 0000-0002-7426-9999 , Subroto, Tungky, Eskin, Dmitry G., Skalicky, Ivan, Roberts, Dan and Tzanakis, Iakovos (2021) Multiphysics modelling of ultrasonic melt treatment in the hot-top and launder during direct-chill casting: Path to indirect micro-structure simulation. Metals, 11 (674). pp. 1-14. ISSN 2075-4701 (Online) (doi:https://doi.org/10.3390/met11050674)

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Abstract

This study concerns the numerical simulation of two competing ultrasonic treatment (UST) strategies for microstructure refinement in direct-chill (DC) casting of aluminium alloys. In the first, more conventional, case, the sonotrode vibrating at 17.3 kHz is immersed in the hop-top to treat the sump melt pool, in the second case, the sonotrode is inserted between baffles in the launder. It is known that microstructure refinement depends on the intensity of acoustic cavitation and the residence time of the treated fluid in the cavitation zone. The geometry, acoustic field intensity, induced flow velocities, and local temperature are the factors which effect this treatment. The mathematical model developed in this work couples flow velocity, acoustics modified by cavitation, heat transfer and solidification at the macroscale, with Lagrangian refiner particles used to determine (a) their residence time in the active zones, and (b) their eventual distribution in the sump as a function of the velocity field. This is the first attempt at using particle models as an efficient, though indirect, alternative to microstructure simulation, and the results indicate that UST in the launder, assisted with baffle separators, yields a more uniform distribution of refining particles, avoiding the strong acoustic streaming jet that, otherwise, accompanies hot-top treatment and may lead to strong segregation of refining particles. Experiments conducted in parallel to the numerical studies in this work appear to support the results obtained in simulation.

Item Type:	Article
Additional Information:	© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Uncontrolled Keywords:	Ultrasonic processing, DC casting, Cavitation, Lagrangian tracking
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Centre for Numerical Modelling & Process Analysis (CNMPA) Faculty of Engineering & Science > Centre for Numerical Modelling & Process Analysis (CNMPA) > Computational Science & Engineering Group (CSEG) Faculty of Engineering & Science > School of Computing & Mathematical Sciences (CMS)
Last Modified:	23 May 2022 10:00
URI:	http://gala.gre.ac.uk/id/eprint/32230

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