Phase-Field Simulation of Dendritic Growth and Additive Effects during Methane Hydrate Crystallization

Accurately characterizing the phase transformation and growth process of natural gas hydrates is of critical importance for their large-scale resource extraction and safe, efficient pipeline transportation. Based on the KKS phase-field theory, this paper proposes a coupled multiphysics field model integrating the phase field, solute field, and temperature field to simulate methane hydrate growth. The model simulates the dynamic process of methane hydrate dendritic growth, with a focus on investigating the mesoscale effects of thermodynamic conditions and additives on growth morphology and kinetics. The results show that the simulation outputs agree well with the classical Ivantsov theory, validating the model’s reliability in describing interfacial coupling dynamics. The study finds that the undercooling degree significantly regulates dendrite morphology and growth rate. When the undercooling increases from 12 to 16 K, the growth area increases by approximately 115%. Crystal anisotropy and interfacial perturbations jointly modulate the branching structure. Using TBAB as an example additive, it is found that its addition can enhance the phase transformation driving force by reducing the solute chemical potential. The optimal promoting effect is observed at a concentration of 0.05 wt %, where the dendritic growth area and rate increase by 16.3% and 13.8%, respectively, consistent with actual experimental data. This research provides a theoretical tool for understanding the mesoscale mechanisms of hydrate growth and offers an extensible simulation framework for the rational design and optimization of additives.