hollow droplet. After this the temperature of the newly solid deposit at the substrate/droplet interface decreases for some time after that it is almost constant until the whole droplet solidified. In case of hollow droplet cooling rate is higher as compared to dense droplet, it’s because the latent heat is transferred to substrate as well as in counter jet in case of hollow dropletFigure 4-3 compared the solid- liquid interface speed for the case of dense droplet and hollow droplet. It can be observed that initially the interface speed is same for the hollow droplet and dense droplet case. As the time progress its value for the case of hollow droplet is higher due to occurrence of counter jet and then again is almost same as the case of dense droplet. In the initial time in case of hollow droplet, interface speed is governed by cooling rate due heat transfer in to substrate but as time progresses interface speed is governed by cooling rate due heat transfer in to substrate as well as released latent transferred to counter jet in case of hollow droplet. But in case of dense droplet, interface speed is governed by cooling rate due heat transfer into substrate only.