Solidification of a liquid drop enclosing a bubble on an inclined surface

In the present paper, we report the numerical results of the solidification process of a liquid drop enclosing an air bubble, i.e., a hollow drop, on an inclined surface. The surface is tilted from 0 degrees (corresponding to a horizontal surface) to 90 degrees (corresponding to a vertical surface), and the contact angle of the drop ranges between 60 degrees and 130 degrees. The drop is deformed while solidification happens in the presence of volume expansion. This volume change results in the formation of a tip at the drop top. The tip becomes more asymmetric as the tilting angle, i.e., the surface angle, increases. However, the solidification time is not affected by the surface angle. During the initial stage of solidification, the drop liquid accumulates to the bottom, by gravity, and thus results in lowering the bubble position. The bubble then moves upwards due to buoyancy force. It stops moving as it is trapped by solidification. A larger bubble reduces the tip shift. We also consider the effect of the Bond number and the Stefan number on solidification.