An experimental study for impact of a drop onto a particle in mid-air: The influence of particle wettability

Drop impact onto a particle in mid-air is a fundamental physical phenomena relevant to many applications involving a fluidized bed, for example, refining of heavy oil or coating of drug particles for pharmaceutical industry. A literature analysis shows that previous studies were focused on collisions of drops with static particles of either spherical or non-spherical shapes. This paper reports on experiments conducted at similar impact conditions with water drops and particles made of hydrophobic (polystyrene) and hydrophilic (soda-lime glass) materials. It was observed that at similar Weber numbers, wettability of the particle plays a key role in transition between collision outcomes with formation of a liquid lamella and ligaments. Present investigation is one of the first which reveals quantitative aspects for dynamics of the lamella and liquid ligaments in a particular case of mid-air collisions.