Numerical simulation of melting and shape evolution characteristics of non-spherical ice crystals

To investigate the melting characteristics and shape evolution of non-spherical ice crystals in hot airflow environment, a melting model for non-spherical ice crystals was developed based on a decoupling strategy for flow and phase-change heat transfer, enabling a solution to the complex heat transfer problem involving gas-liquid-solid coupling. The results demonstrate that the proposed model accurately predicts the shape evolution process during ice crystal melting, and the predicted melting time agrees well with experimental results, with a deviation of ±15%. The shape evolution of non-spherical ice crystals undergoes three distinct stages: an initial warming stage where the shape remains stable, a partial water coverage stage where liquid water partially covers the ice core surface, and a complete water coverage stage where the ice core is fully enveloped. The initial aspect ratio is identified as the key factor governing the shape evolution during melting. A larger initial aspect ratio results in a longer time required for the ice crystal to evolve into a spherical shape. Furthermore, an empirical correlation between dimensionless sphericity and the melting ratio was established, overcoming the limitations of the traditional linear approximation model for high-aspect-ratio (initial aspect ratio λ > 2) ice crystals and significantly improving computational accuracy.