On the Lifetime of Non-coalescent Levitated Droplets

It is shown that a droplet will levitate over the liquid surface for 50-700 ms when released from a critical height 1.5-4 times the droplet diameter. While releasing a droplet out of this range will lead to direct submersion. Additionally, it is shown that by applying a temperature difference between the liquid pool and droplet it is possible to elongate the levitation time of that droplet as it pulls the surrounding air molecules between the drop and the pool surface. Lastly, the thickness of the air gap is calculated theoretically for a range of temperatures and compared with experiments. Surprisingly, larger temperature difference between droplet and surface causes an increase in the thickness of the air gap. It is also found that the size of droplet and type of fluid can significantly affect the lifetime of non-coalescent drops.