Shevtsova: Influence of Interfacial Heat Exchange on the Flow Organization in Liquid Bridge

During the last few decades, convective flows in systems with free boundaries attract much attention from both fundamental and industrial aspects, especially in microgravity-related science. In the terrestrial environment, buoyancy and thermocapillary forces are coupled to cause convection. In addition the motion of ambient gas is very different in terrestrial and microgravity conditions. Although the majority of ground-based experiments were performed in small liquid bridges with silicone oils, it is rather confusing to compare quantitatively the results of different researchers. The discrepancy between critical parameters is quite large. There are several reasons for this: difficulties in precise detecting of the onset of oscillations, difficulties in accurate determination of the relative volume of liquid bridge, which leads to additional deformation of free surface and, of course, different experimental conditions. It covers anti-wetting agents, temperature regime around the set-up, the temperature of cold rod (as usually heating from above is studied), the heat exchange from the free surface, etc. Our results [1, 2], as well as results of other researchers [3, 4], indicate extreme sensitivity of the liquid bridge to environmental conditions. However, a deep understanding of the physical mechanism of these effects is still missing and is the target of proposed study in the frame of forthcoming ESA program.