溢油事故中油品的扩散会严重污染海洋，若同时存在火源，则会发生伴随油品扩散行为的流淌火现象，引起严重的溢油火灾事故。目前关于油品物性及基底环境对溢油扩散行为的具体影响机制的研究仍存在不足。因此，该文采用ANSYS FLUENT软件构建了用于研究溢油扩散过程的多相流模型，针对基底盐度（0 g/kg（去离子水）、20 g/kg、30 g/kg、40 g/kg）、油含水率（0%、20%、40%、60%）、环境温度（20 ℃、30 ℃、40 ℃）3个变量开展了溢油扩散运动模拟研究，以深入揭示盐度、油含水率、温度对油膜扩散行为的影响。结果表明，油膜的扩散运动随基底盐度的增加而显著加快；随着油含水率的增加，油膜在基底的扩散直径逐渐减小；基于油膜扩散速率云图发现，扩散初期，重力作为主要驱动力，促使油膜中心沿径向快速扩散；随着时间推移，表面张力作为主要驱动力，促使油膜边缘缓慢扩散；随着基底温度增加，油品表面张力减小，油品黏度降低，加剧了油膜的扩散运动；基于幂律函数构建了不同基底盐度、油含水率、基底温度条件下油膜扩散直径的预测公式。数值模拟分析结果为揭示不同环境影响因素下溢油扩散动态行为提供了重要的理论支撑。

Objective: Oil spills in the ocean resulting from accidents can cause significant water pollution across large areas. When a dispersed oil film on the water surface comes into contact with an ignition source, it may ignite and lead to a severe marine fire. Currently, research on the microscopic mechanisms through which oil properties and substrate environments influence the dynamic diffusion behavior of oil is relatively limited. Methods: In this study, a multiphase flow model was developed using the ANSYS FLUENT software to investigate the dynamic evolution and diffusion mechanisms of oil on the substrate under various influencing factors. Using numerical simulation, diffusion kinetics of oil films on substrates with different properties were studied under various environmental conditions, focusing mainly on three variables: (1) substrate salinity (deionized water, 20 g/kg, 30 g/kg, and 40 g/kg), (2) water content of the oil (crude oil, 20%, 40%, and 60%), and (3) substrate temperature (20 ℃, 30 ℃, and 40 ℃). This study mainly emphasizes the effects and regulatory roles of these three influencing factors on the dynamic diffusion behavior of oil films. Results: The results indicate a direct correlation between the salinity of the substrate and the diffusion rate of the oil film. Increased salinity elevates the density and surface tension of the substrate, promoting the diffusion of the oil film. The water content of oil affects its physical properties, such as density, viscosity, and surface tension. Higher water content leads to higher viscosity, which inhibits the diffusive movement of the oil on the substrate and ultimately reduces the diameter of the diffused oil film. Analysis of the oil film diffusion rate contour map revealed that during the initial diffusion stage, gravity acts as the primary driving force, causing rapid diffusion in a radial direction. Over time, surface tension dominates and slows down the diffusion process at the oil film edges. With an increase in substrate temperature, the viscosity and surface tension of the oil decrease, thus promoting the diffusion of the oil film. The ratio of the diameter to the thickness of the oil film also affects the diffusion trend. At higher temperatures, this ratio varies significantly, indicating vigorous movement of the oil film in the initial stages. Formulas for predicting the diameter of the diffused oil film under varying conditions of salinity, water content, and temperature were derived based on power-law functions and showed good agreement with simulation results. Conclusions: Oil spills in marine environments spread at a faster rate with an increase in salinity. The water content in oil films also affects the diffusion rate: oil films with high water content spread at a slower rate compared with those with low water content. Furthermore, water temperature has a significant effect on oil spilling; high water temperature makes the diffusion behavior of the oil film more intense. Numerical simulation characterizes the dynamic diffusion features of oil under diverse environmental conditions, laying a theoretical foundation for the prediction of slick diffusion of oil during spill incidents.