Magnetic field-induced interfacial pattern formation in thin ferrofluid drops.

This study investigates the pattern-forming behavior of ferrofluid droplets under the influence of radial magnetic fields. The experimental setup involves depositing initially circular ferrofluid drops surrounded by an immiscible nonmagnetic fluid on a plate with an electromagnet placed below. Through systematic experimentation and theoretical analysis, we explore the effects of two distinct radial magnetic fields on the outer and inner shapes of the droplets. Results reveal the emergence of various intricate interface patterns, including spike-like structures and fingerlike protrusions, as the magnetic Bond number and droplet initial diameter vary. The experimental observations are supported by theoretical predictions derived from mode-coupling differential equations, which provide insight into the underlying dynamics governing pattern formation. This study sheds light on the complex interplay between magnetic and hydrodynamic effects in ferrofluid systems, with implications for diverse applications ranging from microfluidics to biomedical engineering. [ABSTRACT FROM AUTHOR]