Modelling of saline water droplet freezing on a cold surface and machine‐learning approximation of the numerical solution

Sea‐spray ice accretion on marine infrastructure in cold regions poses a significant operational hazard, yet the mechanisms governing saline droplet freezing upon contact with equipment surfaces remain incompletely understood. We experimentally investigate the impact of free‐falling saline droplets (30‰ salinity) with diameters ranging from 1.43 to 9.2 mm on cold steel surfaces, maintained at −5, −10, and −15°C with an initial droplet temperature of 8°C. High‐speed imaging reveals that, under specific conditions, post‐impact droplets freeze as uniform thin disks. We develop a one‐dimensional model of disk freezing on a cold surface that accounts for the porosity of the formed saline ice. The thermophysical properties of the solid (ice) and liquid (brine) phases are described using validated empirical correlations. The governing equations are formulated in a moving coordinate system, thereby eliminating the need for computational domain remeshing. Model predictions are demonstrated through numerical examples and qualitatively compared with experimental observations. A machine learning surrogate model is also developed to enable rapid prediction of droplet freezing dynamics on cold surfaces.