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Magnetic damping of levitated liquid droplets in AC and DC field

Magnetic damping of levitated liquid droplets in AC and DC field

Bojarevics, Valdis, Roy, A., Easter, S. and Pericleous, Koulis A. (2009) Magnetic damping of levitated liquid droplets in AC and DC field. 6th International Conference on Electromagnetic Processing of Materials, EPM 2009. Forschungszentrum Dresden-Rossendorf, Dresden, Germany. ISBN 978-3-936104-65-3

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Abstract

The intense AC magnetic field required to produce levitation in terrestrial conditions, along with the buoyancy and
thermo-capillary forces, results in turbulent convective flow within the droplet. The use of a homogenous DC magnetic
field allows the convective flow to be damped. However the turbulence properties are affected at the same time, leading
to a possibility that the effective turbulent damping is considerably reduced. The MHD modified K-Omega turbulence
model allows the investigation of the effect of magnetic field on the turbulence. The model incorporates free surface
deformation, the temperature dependent surface tension, turbulent momentum transport, electromagnetic and gravity
forces. The model is adapted to incorporate a periodic laser heating at the top of the droplet, which have been used to
measure the thermal conductivity of the material by calculating the phase lag between the frequency of the laser heating and the temperature response at the bottom. The numerical simulations show that with the gradual increase of the DC field the fluid flow within the droplet is initially increasing in intensity. Only after a certain threshold magnitude of the field the flow intensity starts to decrease. In order to achieve the flow conditions close to the ‘laminar’ a D.C. magnetic field >4 Tesla is required to measure the thermal conductivity accurately. The reduction in the AC field driven flow in the main body of the drop leads to a noticeable thermo-capillary convection at the edge of the droplet. The uniform vertical DC magnetic field does not stop a translational oscillation of the droplet along the field, which is caused by the variation in total levitation force due to the time-dependent surface deformation.

Item Type: Book Section
Additional Information: This was a keynote paper and forms part of the Proceedings of the 6th International Conference on Electromagnetic Processing of Materials, EPM2009, held 19-23 October 2009, in Dresden, Germany. EPM2009 was jointly coordinated by the Institute of Safety Research of the Forschungszentrum Dresden-Rossendorf (FZD), Germany and SIMaP/EPM Grenoble, France.
Uncontrolled Keywords: magnetic levitation, MDH, K-Omega turbulence model
Subjects: T Technology > TS Manufactures
T Technology > TN Mining engineering. Metallurgy
Q Science > QA Mathematics
Pre-2014 Departments: School of Computing & Mathematical Sciences > Centre for Numerical Modelling & Process Analysis
School of Computing & Mathematical Sciences
School of Computing & Mathematical Sciences > Department of Computer Systems Technology
School of Computing & Mathematical Sciences > Department of Mathematical Sciences
School of Computing & Mathematical Sciences > Centre for Numerical Modelling & Process Analysis > Computational Science & Engineering Group
Related URLs:
Last Modified: 14 Oct 2016 09:04
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
URI: http://gala.gre.ac.uk/id/eprint/1494

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