This case can be assimilated to an ice cube placed in a glass of water. The description of the configuration is the following :
That is to say that contrary to reality, the ice cube is totally submerged.
A more realistic case, would have been to put the cube between a layer
of air and another of water. Nevertheless this simulation should give a
good idea of the melting time.
The results obtained are not satisfying at all. Indeed, with a thermal initial condition of 270 K for the ice and 293 K as the boundary condition, after only one iteration the value of the ice temperature explode to 253 K. Due to a lack of time, it has not been possible to find where the problem come from, so if you are interested in ....