Impact Characteristics of a Carbonated Water Droplet on Hydrophobic Surface

Carbonated water drops impact on a hydrophobic surface is examined. The influence of CO₂ gas bubbles in droplet fluid on impacting droplet characteristics, such as spreading rates and restitution coefficient, are explored. The predictions of droplet wetting diameter and spreading rates are validated through the experimental data obtained from highspeed recording. The findings reveal that predictions agree well with the experimental data. CO₂ gas bubbles in the droplet are compressed by the total impact pressure of the droplet liquid while slightly reducing the gas bubble sizes. The small size of close by bubbles at high pressure can merge forming large size bubbles, which occur toward the end of droplet spreading and retraction periods. The pressure increase in the fluid gives rise to the increased vertical height of the droplet and slightly reduces the droplet contact diameter on the impacted surface. The work done during the compression of CO₂ gas in bubbles lowers the restitution coefficient of the droplet after the retraction period.