Title image - The Centre for Numerical Modelling and Process Analysis

The Computational Science & Engineering Group

Selected Publications

TITLE:
The effect of secondary arm growth on thermoelectric magneto-hydrodynamics.

AUTHORS:
A. Kao and K.A. Pericleous

JOURNAL:
Magnetohydrodynamics J., Vol. 48, No. 2, pp. 361–370, 2012

DESCRIPTION:
This article examines the influence of external magnetic fields on the microstructure of alloys, in a fully coupled, 3D, flow, EM field and crystal growth simulation. In particular, the unexplored phenomenon of thermoelectric current interaction with the field to induce solute micro-convections at the scale of secondary and tertiary arms, offers a deterministic control for altering microstructure, producing materials with specific properties. This research led to EPSRC EP/K011413/1, (Disruptive Solidification Microstructures via Thermoelectric Control, £279k) in collaboration with the Diamond UK Synchrotron facility and Manchester University, which aims to observe this effect in situ, in real time.

TITLE:
A numerical model coupling thermoelectricity, magnetohydrodynamics and dendritic growth.

AUTHORS:
A. Kao and K.A. Pericleous

JOURNAL:
Journal of Algorithms & Computational Technology, 6 (1). pp. 173-202. (2012) ISSN 1748-3018

DESCRIPTION:
This article demonstrates the potential of inter-dendritic solute micro-convection generated by crossing thermoelectric currents with an external magnetic field in altering alloy microstructure. These effects have been observed in practice, but not adequately explained. A fully coupled 3D numerical simulation offers an explanation based on the physics of the problem.

TITLE:
Modelling the dynamics of the tilt casting process and the effect of the mould design on casting quality.

AUTHORS:
H. Wang , G. Djambazov , K.A. Pericleous, R.A. Harding, M. Wickins

JOURNAL:
Computers & Fluids, 42 (2011) 92–101

DESCRIPTION:
An important output of the EU FP6 IMPRESS intermetallic materials project (€41M, UG €600k), shows synergy of experiments (Birmingham) and modelling (UG), to develop a unique casting technique for gamma-TiAl blades destined for future RR aeroengines, to replace heavy nickel superalloys. TiAl is notoriously difficult to cast, highly reactive and it has to be defect-free for aerospace application. UG software (from EPSRC GR/N14316/01) simulate this multi-physics process (fluid flow, electromagnetic induction, free surface behaviour, solidification). Follow on projects: TSB ‘COLDMELT’ (UG £141k) and FP7 EXOMET (€19M, UG €400k).

TITLE:
A multi-scale 3d model of the vacuum arc remelting process.

AUTHORS:
K.A. Pericleous , G. Djambazov , M. Ward , L. Yuan , P.D. Lee

JOURNAL:
Metallurgical and Materials Transactions A, Published Online first, March 2013 (DOI: 10.1007/s11661-013-1680-4)

DESCRIPTION:
High quality steel and titanium ingots for aerospace and power generation are produced by Vacuum Arc Remelting (VAR) using a DC arc to melt electrode feed material. The melt pool is stirred by buoyancy and electromagnetic fields. Complex interactions with the solidifying front lead to defects, as in cases where the arc wanders altering flow and temperature. World first 3D coupled macro (UG) plus micro (IC) models implemented through a shared PhD student (Yuan) and EM field measurements (Birmingham), identify causes of common defects (white spot, freckles). EPSRC EP/D505011/1 (UG £169k), industrial partners Rolls-Royce, Corus, Wiggins Special Metals.

TITLE:
Toward a Full Simulation of the Basic Oxygen Furnace: Deformation of the Bath Free Surface and Coupled Transfer Processes Associated with the Post-Combustion in the Gas Region.

AUTHORS:
Y. Doh, P. Chapelle, A. Jardy, G. Djambazov, K. Pericleous, G. Ghazal, P. Gardin

JOURNAL:
Metallurgical and Materials Transactions B, Vol. 44, Issue 3, pp 653-670, June 2013

DESCRIPTION:
The Basic Oxygen Furnace (BOF) represents a significant energy user in steelmaking, where optimisation can be achieved by better process understanding. This article stems from a joint UG/Nancy PhD study (Yannick Doh) funded by ArcelorMittal and the French government (ADEME). Greenwich developed a coupled model of the compressible reacting top space containing a supersonic oxygen jet, with bath chemistry, removing carbon to a required tolerance. The model identified the crucial influence of intermediate reactions in the process and the role of fragmented bath material thrown in the top space. ArcelorMittal licensed the model for process optimisation.

TITLE:
Time-dependent modelling and experimental validation of the metal/flux interface in a continuous casting mould.

AUTHORS:
K.A. Pericleous , G. Djambazov , B. Lebon , T.N. Croft , J-F. Domgin and P. Gardin

JOURNAL:
Revue de Métallurgie - Cahiers d'informations techniques, 1. pp. 33-43. ISSN 0035-1563 (Print) 1156-3141 (Electronic)

DESCRIPTION:
The significance of this paper rests on the discovery of a link between internal flow structure and frequency of steel /slag interfacial waves in the continuous casting process for steel plate. The filtering of turbulence models to prevent numerical wave damping is a novelty of the study. Part of long-term collaboration with ArcelorMittal who carried experiments, while Greenwich developed the three-phase model for simulations. The journal article is an extended version of a conference paper that won 1st prize out of 80 submissions at the ATS annual conference (Federation Francaise de l'Acier).

TITLE:
Dynamic Model for Metal Cleanness Evaluation by Melting in Cold Crucible.

AUTHORS:
V. Bojarevics , K.A. Pericleous and R. Brooks

JOURNAL:
Metallurgical and Materials Transactions, B, 2009, v. 40, N 3, 328 – 336. ISSN 1073-5615

DESCRIPTION:
Sampling molten metal to assess the level of impurities without interrupting the manufacturing process is important for industry. Collaboration with the National Physical Laboratory, evaluated this new sampling technique: metal is collected in a small crucible surrounded by an induction coil; electromagnetic Kolin-Leenov forces separate impurities to the surface where they can be counted. Our spectral code SPHINX was used to verify this concept and the process was presented to an industrial club by NPL. This beginning led to EU FP7 projects EXOMET (€19M/€400k) for MMNC production and SIKELOR (€4M/€309k) for silicon recycling from kerf.

TITLE:
Effect of Magnetic Forces on Bubble Transport and MHD Stability of Aluminium Electrolysis Cells.

AUTHORS:
V. Bojarevics, A. Roy

JOURNAL:
Magnetohydrodynamics, 2012, Vol. 48, No. 1, pp. 125–136. ISSN 0024-998X

DESCRIPTION:
Linked to our spectral shallow-layer MHD-VALDIS software for Hall-Herault aluminium electrolysis cells, this study looks at the interaction of gas bubbles with anode current. This is not a well-understood phenomenon, which nevertheless influences cell efficiency. The software is essential for cell stability calculations and found worldwide use for the design of energy-efficient new cells in Russia, Dubai, China, and the USA.

TITLE:
Levitated Liquid Dynamics in Reduced Gravity and Gravity-Compensating Magnetic Fields.

AUTHORS:
V. Bojarevics and R.W. Hyers

JOURNAL:
JOM: Journal of the Minerals, metals, and Materials Society - Springer (JOM), 2012, Vol. 64, No. 9, pp. 1089-1096. DOI: 10.1007/s11837-012-0417-y

DESCRIPTION:
Output of the ELIPS materials project SOL-EML (ESA and NASA funded international topical interest group of aerospace organisations), where Greenwich contributes as the modelling partner, using techniques develop in the FP7 IMPRESS project and EPSRC GR/L97483/01. The analysis gives insights to the internal mechanisms of fluid levitation that cannot be observed directly, including classical levitation experiments for property measurements, Marangoni convection in microgravity, turbulence damping in combined AC and DC fields. Modelling was used to assist stabilisation of ISS levitation device designed by ASTRIUM.

TITLE:
Modelling of electromagnetic levitation – consequences on non-contact physical properties measurements.

AUTHORS:
J. Etay , P. Schetelat , B. Bardet , J. Priede, , V. Bojarevics and K. A. Pericleous

JOURNAL:
High Temperature Materials and Processes, 27 (6). pp. 439-447. ISSN 0334-6455

DESCRIPTION:
A research collaboration with the MADYLAM laboratory in Grenoble and the Institute of Physics in Riga, resulted in an extensive study of the flow parameters affecting the accuracy of property measurements by EM levitation, especially under terrestrial conditions. In particular, the role of turbulence was highlighted as a cause of error in viscosity measurements, but also in measurements of thermal conductivity. Bojarevics supervised the Grenoble PhD student Benoit Bardet, who was seconded to Greenwich for this task.