Spreading process and characteristics of silicone oil with multi-viscosities on calm liquid surface with low temperature: Spreading length, stable thickness and morphology

Abstract

Oil spreading on the sea has been a great focus, especially along with the intensification of oil development activities in arctic regions, leading to an increase in the frequency of oil spills in extremely cold regions. Currently, the effect of extreme low temperature on oil spreading behavior has not been fully studied, and the applicability of existing models of oil spreading characteristics in low temperature scenarios is not clear. An experimental platform was customized to set up low temperature liquid substrate environments (−20∼20 °C). A series of oil spreading experiments of silicone oil with viscosities of 50, 100, 350 and 1000 cs and five released volumes (1–5 ml) on low temperature substrates were carried out. The effects of experimental variables including temperature, viscosity and volume on oil spreading characteristics of spreading length, stable thickness, morphology, and cone angle were investigated. The entire spreading process of oil was displayed from the top and side views, and gave the variation curves of oil thickness and cone angle with time. Summarized the spreading law for multi-viscosity silicone oils, the values of the pre-exponential coefficient and the power-law exponent were determined, and detailed formulas for calculating the spreading length was proposed. An stable thickness prediction model that integrates all the forces on the oil spreading process was constructed, including surface tension, viscous force, inertia force and gravity. These forces all weakening with time, especially the inertial and viscous forces, which contain time terms, and weaken the most. The heat transfer between the oil and the liquid substrate was also monitored and discussed in the experiments, proposed that low temperatures may hinder the spreading behavior of the oil by decreasing the spreading coefficient of the oil. The findings of this study can provide a theoretical support for the oil spill cleanup.