Weak solutions and weak-strong uniqueness for a thermodynamically consistent phase-field model

In this paper, we prove the existence of weak solutions for a thermodynamically consistent phase-field model in two and three dimensions of space. We use a notion of solution inspired by previous contributions on the same model and where the pointwise internal energy balance is replaced by the total energy inequality complemented with a weak form of the entropy inequality. Moreover, we prove the existence of local-in-time strong solutions and, finally, we show weak-strong uniqueness of solutions, meaning that every weak solution coincides with a local strong solution emanating from the same initial data, as long as the latter exists.