[Help] How to define a variation of volume during a phase change in Abaqus?

Dear friends,

I am a beginner in using Abaqus. Now I am doing a project which calls for a simulation of the phase change probleme (two demensional Stephan problem).

I did a simple simulation with water, more prescisely a water slab of 10 C at the left I impose a temperature -10 C, so I got the results of the profils of temperature in every increment of time. 

The next setp for me is to study the expension of volume when phase changing (at 0 C), we know that at 0 C, a mass of water will expend when freezing (but the temperature donnot change), I'd like to know if I could set a parametre in Abaqus to realise this point? Or should anyone know other ways to do this?

One thing is clear is that the "density dependent of temperature" is not allowed to use in doing such sunulation. 

Any idea or suggestion would be helpful!

Thank you in advance.

Deqi LIU