solidifies completely at about 5.4 µs and in the case of hollow droplet it takes more than 30 µs as counter jet takes time to come back on substrate. It can be observed from the Figure 4- 1 that evidently, the predicted rupture of the droplet shell (1.2 µs) in case of hollow droplet. Recoiling can be also seen in case of hollow droplet at time 2.2 µs but in case of dense droplet it can be seen at time 2.5 µs.
In case of hollow droplet more air entrapment occurs due to rupture of the droplet shell due to counter jet. Solidification is at faster rate in case of hollow because of counter jet due to this thickness is larger as compared to dense droplet solidification, where no counter jet is present at any instant of time which promote more splashing.
Figure 4-2 shows the time evolution of droplet bottom temperature. It can be seen that before the start of solidification the temperature decreases as the heat is transfer from the liquid to solid substrate. But after solidification begins, the temperature is constant in case of dense droplet for very short interval of time, this is due to release of latent heat during solidification, its due to slow solidification rate as compared to hollow droplet, but in case of hollow droplet it is not observed its due high heat transfer rate. In case dense droplet latent heat released is transferred to substrate while it is transferred to substrate as well as in counter jet in case of
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