Influence of Ferrofluid Drop Shapes on Cavity Formation During Impact on a Liquid Pool

Ferrofluids are liquids that become strongly magnetized in the presence of a magnetic field, and they have applications in various fields including medical devices, electronics, and mechanical components. This experimental study examines how magnetic fields can change the shapes of impacting ferrofluid drops. The drops were made to fall into a pool of water, influenced by an electromagnet positioned beneath the tank. By adjusting the electromagnet's pulse duration through an external trigger box, the drops were shaped into either prolate or oblate forms before impact. The electromagnet was deactivated just before the drops hit the water, preserving their shapes while halting magnetic effects. As oil-based ferrofluids do not mix with water, the shape of the drop affected the formation and evolution of the resulting cavities. We measure the maximum depth and diameter of these irregular-shaped cavities in relation to impact velocity and drop shape. Findings indicated that drops with prolate shapes created deeper cavities compared to spherical and oblate drops.