Numerical simulations on corner melting of solid–liquid phase change for thermal management based on lattice Boltzmann model

Solid–liquid phase change materials (PCMs) are widely employed as a passive thermal storage solution in the thermal management of electronic devices. However, the intricate internal layouts of electronics often lead to localized thermal accumulation and steep temperature gradients, resulting in highly non-uniform melting and degraded energy utilization. A significant challenge lies in accurately capturing the coupled effects of localized heating, buoyancy-driven natural convection, evolving phase interfaces, and complex boundary-layer development for PCM-based thermal management systems. In this work, the corner melting behavior induced by localized heating is analyzed within multi-wall heating and multi-size structural configurations, using Lattice Boltzmann Method (LBM). By varying the cavity aspect ratio γ, evolutions of temperature distribution, convective structure, and boundary-layer interactions during melting dynamics and energy storage efficiency are quantitatively examined. The results indicate that for narrow cavities with aspect ratios of 0.75, 0.5, and 0.25, the melting process is primarily governed by heat conduction, with limited contributions from natural convection and boundary effects; when the Fourier number reaches 10, the corresponding energy storage efficiency is enhanced by 11.0%, 36.4%, and 48.0%, respectively, compared with that of the square cavity. In contrast, for wider cavities with aspect ratios of 1.33, 2, and 4, the development of complex vortex structures intensifies thermal asymmetry and suppresses the melting rate, leading to liquid phase fractions of only 84%, 81.6%, and 62.5% at a dimensionless time of 40. Overall, the results demonstrate a strong dependence of melting behavior on cavity geometry under localized heating conditions, suggesting that an aspect ratio in the range of 0.5 to 1 maximizes melting uniformity and latent heat utilization, while maintaining an aspect ratio close to 2 in wider cavities helps alleviate excessive vortex formation and ensures stable thermal performance.