Effects of magnetic field on the spreading dynamics of an impinging ferrofluid droplet.

This paper presents a comprehensive experimental study of the effects of vertically and horizontally applied magnetic fields on the dynamics of magnetowetting and the formation of satellite droplet. Besides explaining the physics of the transient variation of different drop shape parameters, the role of a magnetic field on controlling the dynamics of spreading is also presented. Ultimately the magnetic field maneuvers the droplet spreading without altering the surface chemistry. The morphological evolution and dynamics of an impacting ferrofluid droplet has also been studied. By observing the spreading at an appropriate time scale, the contrary spreading behavior of the paramagnetic ferrofluid under the effect of magnetic field is noticed. Special attention is given to the droplet break-up and satellite droplet formation. A universal relationship is presented between the drop shape parameters before and after the impact. The destination and travel path of the satellite droplet is also analyzed in a vertical as well as horizontal magnetic field, which governs the satellite droplet merging with the already deposited parent droplet.