A Generalized Formulation for Evaluation of Latent Heat Functions in Enthalpy-Based Macroscopic Models for Convection-Diffusion Phase Change Processes

摘要

A standard approach for the numerical modeling of macroscopic phase change processes in the convection-diffusion problem is the so-called "fixed-grid enthalpy-based" method. In this method, the enthalpy is related to the liquid volume fraction of fluid in a control volume, which, in turn, determines a porous-medium-like resistance toward fluid flow in the phase changing domain. For accurate prediction of the same, the latent heat content of each computational cell needs to be updated according to the temperature and/ or species concentration values predicted by the macroscopic conservation equations, during each iteration within a time-step. In a physical sense, such an updating attempts to neutralize the difference in the nodal temperature predicted from the energy equation and that dictated by the phase-change considerations. Thus, the enthalpy updating scheme plays a pivotal role in successful implementation of most of the enthalpy-based solution methods.