Superlattice, Rhombus, Square, and Hexagonal Standing Waves in Magnetically Driven Ferrofluid Surface

Abstract

Standing wave patterns that arise on the surface of ferrofluids by (single frequency) parametric forcing with an ac magnetic field are investigated experimentally. Depending on the frequency and amplitude of the forcing, the system exhibits various patterns including a superlattice and subharmonic rhombuses as well as conventional harmonic hexagons and subharmonic squares. The superlattice arises in a bicritical situation where harmonic and subharmonic modes collide. The rhombic pattern arises due to the non-monotonic dispersion relation of a ferrofluid. 47.20.k; 47.54.+r; 05.70.Fh

On the Hill Equation Describing Oscillations of a Ferrofluid Free Surface in a Vertical Magnetic Field

“…However, they failed to show the difference between a case where the magnetic field contains an oscillating part (Mahr 1998;Pi et al 2000) and the one where a classical vertical vibration is combined with a constant vertical magnetic field. In the first situation, the magnetic field introduces the Kelvin force in the momentum balance as proportional to the square of the magnetic field (Hennenberg et al 2009(Hennenberg et al , 2010 whereas for the second one, the classical Faraday vibration adds simply to the gravity external force.…”

Modelling of an Oscillatory Magnetic Field Action on a Ferrofluid Layer

“…This is the main difference between the simplest Faraday vertical vibration and the oscillating magnetic field (Müller 1998;Mahr and Rehberg 1998;Embs et al 2007). Years ago, Mahr and Rehberg (1998) studied such an oscillating magnetic field and exciting experiences appeared recently to illustrate parametric forcing due to an oscillating magnetic field with a very low frequency, in the study of patterns (Pi et al 2000;Ko et al 2002).…”

Microsecond-scale switching time of magnetic fluids due to the optical trapping effect in waveguide structure

“…Ferrofluids, also known as magnetic fluids have generated diverse scientific interests,such as typical dipolar fluids, self-assembled soft materials (Safran 2003), and patternforming systems (Pi et al 2000). On the other hand, such fluids find uses in many areas, such as magnetic sealing, information storage media, magnetic refrigeration (Suslick et al 1996), and various applications in the biomedical field (Kim et al 2006;McCloskey et al 2003).…”