tracking the solidification front
 

I'm having trouble obtaining a plot of the position of the solidification front at each time steph. The model is a simple 2-d transient solidification problem using the melting-solidification model. I need to plot the position of the solidification front, along a certain line (which i can easily specify as a "line-rake") against time.

Anyone familiar with such a task? Can i do it with in-built field functions or maybe with custom field functions? I'd rather not have to resort to user-defined-functions.

Kuba