Abstract
The effects of gravity were investigated for spike pattern formations on the surface of magnetic fluids applying vertical magnetic field. Prior to experiments under microgravity, the mechanism of spike pattern formation was investigated under 1 go condition. Changes of spike patterns were investigated on the removal of gravity and on the application of gravity, which were realized by the drop tower facility in Kamisunagawa, Hokkaido, Japan. On removal of gravity a few spikes appear on even the flat surface under 1 go condition of magnetic fluids. The equilateral hexagonal pattern of spikes under a weak magnetic field is changed into the square pattern due to the removal of gravity. The square pattern of spikes under a strong magnetic field is changed into the equilateral hexagonal pattern under overgravity during the damping of the free fall. These are the first observations on the gravity induced transitions, and are discussed on the instability of free surface of magnetic fluid.
