The oscillation of a falling ferrofluid droplet induced by a nonuniform magnetic field

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL Experimental Thermal and Fluid Science Pub Date : 2024-10-30 DOI:10.1016/j.expthermflusci.2024.111351

Guiye Wen , Yongqing He , Feng Jiao

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Abstract

Understanding the droplet size and shape control mechanism in a magnetic field is critical for precisely manipulating ferrofluid droplets. Here, we conducted an experimental investigation on the dynamic behavior of a falling ferrofluid droplet under a nonuniform magnetic field produced by current coils. We observed an interesting phenomenon: the uneven distribution of the magnetic field and the jump in magnetic properties at fluid interfaces will cause the Laplace pressure difference on the droplet surface, stimulating the droplet’s oscillation. We also use the Laplace pressure difference equation and the interfacial tension coefficient correlation to model the deformation of ferrofluid droplets and determine the oscillation frequencies and deflection angles. The droplets’ oscillation frequency is related to the magnetic Bond number: f∼

{Bo}_{m}^{- 0.523 \sim - 0.501}

. The deflection angle of the droplet is further diminished by the superposition of a viscous shear moment and a magnetic moment (7.41^°∼12.90^°). Our research lays the groundwork for precise ferrofluid droplet manipulation in drug delivery and soft robots.

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非均匀磁场诱导的下落铁流体液滴的振荡

了解磁场中液滴大小和形状的控制机制对于精确操纵铁流体液滴至关重要。在这里，我们对铁流体液滴在电流线圈产生的非均匀磁场下的动态行为进行了实验研究。我们观察到一个有趣的现象：磁场的不均匀分布和流体界面的磁性跃迁会在液滴表面产生拉普拉斯压差，从而刺激液滴振荡。我们还利用拉普拉斯压差方程和界面张力系数相关性建立了铁流体液滴的变形模型，并确定了振荡频率和偏转角。液滴的振荡频率与磁邦德数有关：f∼Bom-0.523∼-0.501。液滴的偏转角因粘性剪切力矩和磁矩的叠加而进一步减小（7.41°∼12.90°）。我们的研究为在药物输送和软机器人中精确操纵铁流体液滴奠定了基础。

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来源期刊

Experimental Thermal and Fluid Science 工程技术-工程：机械

CiteScore

6.70

自引率

3.10%

发文量

159

审稿时长

34 days

期刊介绍： Experimental Thermal and Fluid Science provides a forum for research emphasizing experimental work that enhances fundamental understanding of heat transfer, thermodynamics, and fluid mechanics. In addition to the principal areas of research, the journal covers research results in related fields, including combined heat and mass transfer, flows with phase transition, micro- and nano-scale systems, multiphase flow, combustion, radiative transfer, porous media, cryogenics, turbulence, and novel experimental techniques.