Multiple-relaxation-time total enthalpy lattice Boltzmann model for liquid-vapor phase change
In this paper, a multiple-relaxation-time (MRT) total enthalpy lattice Boltzmann (LB) model is proposed for liquid-vapor phase change. The pseudopotential LB method is employed to describe the liquid-vapor multiphase dynamics, while the thermal field is solved using an MRT LB formulation with total enthalpy as the evolution variable, thereby incorporating sensible and latent heat into a unified framework. A latent heat expression based on the equation of state (EOS) is further derived to provide a thermodynamic reference for its specification. Multiscale analysis demonstrates that the proposed model recovers the target macroscopic energy equation without introducing the nonlinear thermodynamic source term commonly required in temperature-based formulations, thereby avoiding the explicit evaluation of $\nabla\cdot\mathbf{u}$. The model is validated through free droplet evaporation, droplet evaporation on a heated surface, and bubble growth and departure during boiling, showing good agreement with published results. Simulations with different prescribed latent heats are further conducted in all three cases, demonstrating that the latent heat can be independently specified according to the physical conditions considered without altering the equation of state.