Keywords: magnetic levitation, high direct current magnetic field, material properties measurement, computational fluid dynamics, magnetohydrodynamics, free surface.

A high DC magnetic field can be used to levitate liquid droplets in terrestrial conditions, as is known from experiments [1,2]. The DC magnetic levitation mechanism is considerably different from the AC case [3], where an intense turbulent flow is generated as a consequence of the rotational nature of the electromagnetic force. In DC magnetic levitation the force distribution is a potential function, which permits analytical solutions in particular cases [4]. The dynamic interactions of the flow with the oscillating interface, confined by the magnetic force, are analysed using a multi-physics numerical model for simulating the time dependent liquid metal and the magnetic field generated by currents in the coil system [5]. The numerical simulations demonstrate the possibility of levitating diamagnetic droplets in strictly controllable conditions permitting the material properties measurement from experimental observations.

Two different coil arrangements are analysed using the numerical code to model the DC magnetic levitation of a water droplet. The levitation of liquid in controllable conditions is achievable but requires careful optimisation of the electromagnetic and gravity force balance. The fluid velocities, generated by the magnetic force modification due to the liquid surface oscillation in the strong gradient field, are small in magnitude and remain in the laminar regime.

1

E. Beaugnon, R. Tournier, "Levitation of Water and Organic Substances in High Static Magnetic Fields", Journal de Physique III, 1(8), 1423-1428, 1991. doi:10.1051/jp3:1991199

2

D. Chatain, D. Beysens, K. Madet, V. Nikolayev, A. Mailfert, "Study of Fluid Behaviour under Gravity Compensated by a Magnetic Field", Microgravity Science and Technology, 18(3-4), 196-199, 2006. doi:10.1007/BF02870408

3

I. Egry, A. Diefenbach, W. Dreier, J. Piller, "Containerless processing in space - thermophysical property measurements using electromagnetic levitation", Int. J. Thermophys., 22, 569-578, 2001. doi:10.1023/A:1010753805462

4

S. Easter, V. Bojarevics, K. Pericleous, "Determining Surface Tension Using DC Magnetic Levitation", Proceedings 6th Int. Conf. Electromagnetic Processing of Materials, Dresden, 723-726, 2009.

5

V. Bojarevics, K. Pericleous, "Modelling Electromagnetically Levitated Liquid Droplet Oscillations", ISIJ International, 43(6), 890-898, 2003. doi:10.2355/isijinternational.43.890

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