Heat transfer and fluid flow in molten pool

Hi, all, I'm new to COMSOL and want to do a project to simulate the molten pool forming and fluid dynamics within this pool. Currently I 've tried 2 ways to model this process:
1) Heat transfer in solid with phase change and laminar flow method
2) Conjugate heat transfer and deformed geometry method

So, which one is the suitable way to model this? Any other idea or suggestion about this problem?

Thanks for your help~