Miscible ferrofluid patterns in a radial magnetic field

Pattern formation in a miscible ferrofluid system is experimentally investigated. The experiment is performed by immersing a thin ferrofluid droplet in a cylindrical container, overfilling it with a nonmagnetic miscible fluid, and applying an in-plane radial magnetic field. Visually striking patterns are obtained whose morphologies change from circular at zero field to complex starburstlike structures at finite field. The evolution of miscible ferrofluid droplets of various initial diameters subjected to different magnetic-field strengths is considered. Proper rescaling of the experimental data indicates that the time evolution of the droplets' area increments obeys a universal 4/3 power-law behavior at long times.