Magnetic compensation of gravity in fluids: performance and constraints

Mailfert, A.; Beysens, Daniel; Chatain, D.; Lorin, C.

doi:10.1051/epjap/2015150089

Cited by 7 publications

(4 citation statements)

References 36 publications

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“…In the case of the 1 mm spherical permanent magnets that are studied here, these inhomogeneities in the magnetic induction gradient produce a 5% variability in the effective gravity value for Case g * , and an effective gravity between g = 9.5 m s −2 and 9.8 m s −2 for Case g 0 . The presence of oscillations in the magnetic field can be explained as the interference between the higher harmonics that compose the total magnetic induction of each coil, as observed in the literature 20 . The interaction between these higher harmonics can be modified considerably by small errors in the coil positioning.…”

Section: Magnetic Field Productionmentioning

confidence: 79%

“…These are apart from the study of particles in conductive fluids under the influence of external magnetic inductions, that are central to a number of industrial situations, for instance clean metal production 19 . On the other hand, the profiles of the external magnetic induction needed to obtain a constant vertical force that can counteract gravity in a number of scenarios such as, for example, liquid helium or oxygen were also studied [20][21][22][23] . With all these tools in hand, some progress has also been made in the particular situations that interest this work: paramagnetic/ferromagnetic or permanently magnetised particles in a weak diamagnetic liquid (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Tuning particle settling in fluids with magnetic fields

Cabrera-Booman,

Plihon,

Cal

et al. 2024

Exp Fluids

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A magnetic field (MF) is generated to modify gravity in a laboratory. The MF produces a vertical force that counteracts the gravitational field on a magnetic sphere. The perpendicular spin of particles is blocked, thus allowing spin solely around the direction of the MF. The settling of spherical magnets in a quiescent flow with a particle density of 8200 kg/m 3 and Galileo number (Ga) in the range [100, 280] was studied experimentally. The results obtained by varying Ga via gravity modification to those obtained with nonmagnetic spheres where Ga is modified by varying viscosity are compared. Findings showed that there is no significant difference in the trajectory angle between magnetic and non-magnetic cases, suggesting that the method for compensating gravity does not produce any spurious effect and that particle spinning has no significant effect on this aspect of the dynamics. Subtle differences in trajectory planarity were observed hinting at a possible dependence on particle spin. Results prove the validity of the method introduced here to change the gravitational strength on particles in fluids.

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Section: Magnetic Field Productionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Tuning particle settling in fluids with magnetic fields

Cabrera-Booman,

Plihon,

Cal

et al. 2024

Exp Fluids

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“…The issue of magnetic interference has been addressed using both software-and hardware-based approaches. In using software, ferromagnetic interference (Naprstek and Lee, 2017;Noriega, 2011;Tolles and Lawson, 1950) and electric 45 current interference (Noriega and Marszalkowski, 2017) can be related to platform attitude and compensated for in real-time or in post-processing. In using hardware, a straightforward approach is to increase the magnetometer-UAS separation.…”

Section: Introductionmentioning

confidence: 99%

Magnetic interference mapping of four types of unmanned aircraft systems intended for aeromagnetic surveying

Tuck¹,

Samson²,

Laliberté³

et al. 2020

Preprint

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Abstract. Magnetic interference source identification is a critical preparation step for magnetometer-mounted unmanned aircraft systems (UAS) used for high-sensitivity geomagnetic surveying. A magnetic field scanner was built for mapping the interference that is produced by a UAS. It was used to compare four types of electric-powered UAS capable of carrying an alkali-vapour magnetometer: (1) a single-motor fixed-wing, (2) a single-rotor helicopter, (3) a quad-rotor helicopter, and (4) a hexa-rotor helicopter. The scanner’s error was estimated by calculating the root-mean-square deviation of the background total magnetic intensity over the mapping duration; averaged values ranged between 3.1–7.4 nT. Each mapping was performed above the UAS with the motor(s) engaged and with the UAS facing in two orthogonal directions; peak interference intensities ranged between 21.4–574.2 nT. For each system, the interference is a combination of both ferromagnetic and electrical current sources. Major sources of interference were identified such as servo(s) and the cables carrying direct current between the motor battery and the electronic speed controller. Magnetic intensity profiles were measured at various motor current draws for each UAS and a change in intensity was observed for currents as low as 1 A.

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“…Experimental and numerical studies with supercritical CO 2 and SF 6 under weightlessness have reported evidences of such instabilities as described in [12][13][14][15]. Experiments with supercritical have also been reported in literature where micro-gravity conditions were artificially simulated by means of a strong magnetic field [16][17][18][19][20][21]. When supercritical close to the critical point is simultaneously quenched and subjected to mechanical vibrations, finger-like structures were observed normal to the direction of vibration.…”

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confidence: 99%

Vibration-induced thermal instabilities in supercritical fluids in the absence of gravity

et al. 2019

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Supercritical fluids (SCFs) are known to exhibit anomalous behaviour in their thermophysical properties such as diverging compressibility and vanishing thermal diffusivity on approaching the critical point. This behaviour leads to a strong thermo-mechanical coupling when SCFs are subjected to simultaneous thermal perturbation and mechanical vibration. The behaviour of the thermal boundary layer (TBL) leads to various interesting dynamics such as thermo-vibrational instabilities, which become particularly ostensive in the absence of gravity. In the present work, two types of instabilities, Rayleigh-vibrational and parametric instabilities, have been numerically investigated under zero-gravity in a 2D configuration using a mathematical model wherein density is calculated directly from continuity equation. Comparison of experimental observations with numerical simulations is also presented. The peculiarity of the model warrants instabilities to be investigated in a more stringent manner (in terms of higher quench percentage and closer proximity to the critical point), unlike the previous studies wherein the equation of state was linearized around the considered state for the calculation of density, resulting in a less precise analysis. In addition to providing physical explanation causing these instabilities, the effect of various parameters on the critical amplitude for the onset of these instabilities is analysed. Furthermore, various attributes such as wavelength of the instabilities, their behaviour under various factors (quench percentage and acceleration) and the effect of cell 2 size on the critical amplitude is also investigated. Finally, a 3D stability plot is shown describing the type of instability (Rayleigh-vibrational or parametric or both) to be expected for the operating condition in terms of amplitude, frequency and quench percentage for a given proximity to the critical point.

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Magnetic compensation of gravity in fluids: performance and constraints

Cited by 7 publications

References 36 publications

Tuning particle settling in fluids with magnetic fields

Tuning particle settling in fluids with magnetic fields

Magnetic interference mapping of four types of unmanned aircraft systems intended for aeromagnetic surveying

Vibration-induced thermal instabilities in supercritical fluids in the absence of gravity

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