Research on the magnetic fluid levitation force received by a permanent magnet suspended in magnetic fluid: Consideration a surface instability

• Published in: Journal of magnetism and magnetic materials Vol. 492; p. 165678
• Main Authors: Yu, Jun, Chen, Duo, Cai, Zhenyu, Li, Decai, Cao, Qianhui, Qian, Leping
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.12.2019; Elsevier BV
• Subjects: Boundary condition; Buoyancy force; Dependence; Interface stability; Levitation; Magnetic fluid levitation force; Magnetic fluids; Magnetism; Permanent magnets; Spikes; Stress tensor; Surface instability; Surface stability; Tensors; Stress tensor; Magnetic fluid levitation force; Boundary condition; Buoyancy force; Surface instability
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2019.165678

•The levitation force of a magnet depends on the boundary interface of magnetic fluid.•The surface instability of magnetic fluid is associated with the levitation force.•The levitation force can be estimated by magnetic fluid spikes. This paper focus on the magnetic fluid levitation force received by a permanent magnet immersed in magnetic fluid under the magnetic field created by the magnet itself. A more understandable equation for calculating the magnetic fluid levitation force is derived using magnetic fluid stress tensor, and the equation concentrates on the boundary interface between magnetic fluid and surroundings. The magnetic fluid spikes appearing over the interface between magnetic fluid and air caused by the surface instability of magnetic fluid is taken into consideration, and the dependence between magnetic fluid levitation force and magnetic fluid spikes is studied. Two groups of experiments are designed, both theoretical analysis and experiments show that the magnetic fluid levitation force relies on the magnetic fluid spikes which indicates that the magnetic fluid spikes can be used to evaluate the magnetic fluid levitation force for the self-levitation of a permanent magnet. The equation presented in this paper are clear in physical meaning and easy to understand.