Marangoni convection in shallow annular pools of silicone oil heated from above

Abstract

A numerical study in a two-dimensional, axisymmetric cylindrical geometry is performed to evaluate the effect of Marangoni convection in shallow liquid layers of silicone oil. The study aims to understand Marangoni convection for a range of temperature gradients (9.0 K, 11.5 K, and 14.0 K), layer depths (4.0 mm, 4.5 mm, and 5.0 mm) under earth gravity (1.0 g), and microgravity (0.5 × 10 −3 g) conditions. The finite element method is used to solve the present problem using COMSOL V5.6 commercial tool. The microgravity studies ensure Marangoni convection dominates natural convection. In the present simulation, it is found that Marangoni convection is influenced more by temperature difference than layer depths as the change in temperature gradient gives a higher velocity deviation than a change in layer depths. In the presence of fluid meniscus, the thermo-capillary force is observed to be less significant in driving the flow as the peak velocity magnitude is observed to get reduced by 60%. From the microgravity study, it is clear that for velocity magnitude at z = 2.5 mm the Marangoni convection contributes to almost 90% of the total convection.