KEYNOTE: Fluid Physics from International Space Station
- Paper number
IAC-19,A2,4,1,x55162
- Author
Dr. Satoshi Matsumoto, Japan, Japan Aerospace Exploration Agency (JAXA)
- Year
2019
- Abstract
The International Space Station (ISS) provides a great opportunity to conduct experiments that can only be achieved there. Therefore, a plenty of experiment has been done utilizing space unique conditions which are intense space radiation, high vacuum at extra vehicle, microgravity and so on. Usually, we are conducting experiments assuming gravity without consciousness. However, in an environment where gravity does not act, it is possible to observe the phenomena more simply and it will be helpful for understanding the true nature. Disappearing the buoyant effect is one of most remarkable in microgravity. The buoyancy convection induced by density difference often appear in materials processing, combustion, and even in cell in life sciences, which means that the fluid physics deeply relates such things. 20 years at NASA, 10 years for JAXA and ESA have passed after starting to utilize the ISS for progress of science and technology. For JAXA, almost 500 experiments have been conducting on the Kibo module since 2008. Experiments on the physical sciences account for 12% of them. In fluid physics, JAXA focuses Marangoni experiment and boiling two-phase flow experiment. Especially, Marangoni experiment has been continuously implemented since the start of utilizing the KIBO, and systematic experiments deepen understanding of phenomena and give insight into control of convection. Marangoni convection is the flow driven by the presence of a surface tension gradient that can be produced by a temperature difference at a liquid/gas interface. It can best be studied in a liquid bridge formed under microgravity conditions. To learn how heat is transferred in microgravity, the convection in a liquid bridge of silicone oil is generated by heating one disc higher than the other, allowing scientists to observe flow patterns that can tell them about how heat is transferred in microgravity. Surface tension is the characteristic of a liquid in which it forms a layer at its surface so that this surface covers as small an area as possible. For example, in the image below, one can see the coin floating on the surface of the water. Surface tension is the force that keeps the heavier coin from sinking. In general, surface tension becomes stronger with decreasing temperature. A trait of Marangoni convection is a surface tension-driven fluid flow in which the driving force is localized at the only surface. When a temperature difference exists along a surface, the surface is pulled toward a low-temperature region.
- Abstract document
- Manuscript document
IAC-19,A2,4,1,x55162.pdf (🔒 authorized access only).
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