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Published on: March 5, 2014
Maximum Spreading of Impacting Ferrofluid Droplets under the Effect of Nonuniform Magnetic Field
Qian-Ping Li1,2, Yi Ouyang1,2, Xiao-Dong Niu1,2
1Key Laboratory of Intelligent Manufacturing Technology, MOE, Shantou University, 243 Daxue Road, Shantou 515063, Guangdong, China.
Abstract:
This article investigates the maximum spreading of ferrofluid droplets impacting on a hydrophobic surface under nonuniform magnetic fields. A generalized model for scaling the maximum spreading is developed. It is observed that, if the magnetic field strength is zero, a ferrofluid droplet not only demonstrates similar spreading dynamics as the water droplet but also obeys the same scaling law for the maximum spreading factor. Therefore, this article emphasizes the effects of magnetic field strength. In this regard, a dimensionless parameter (Nm) is introduced as the ratio between inertial force and Kelvin force, with an assumption that the kinetic energy mainly transforms to thermal energy. This parameter allows us to rescale all experimental data on a single curve with the Padé approximant, which is applicable to a wide range of impact velocities and magnetic field strengths.
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