Marangoni convection is the flow driven by the presence of a surface tension gradient which can be produced by temperature difference at a liquid/gas interface. The convection in liquid bridge of silicone oil is generated by heating the one disc higher than the other. Scientists are observing flow patterns of how fluids move to learn more about how heat is transferred in microgravity.Principal Investigator(s)
IHI Aerospace Company, Ltd., Tomioka, , Japan
Japan Aerospace Exploration Agency (JAXA), Tsukuba, , Japan
Japan Aerospace Exploration Agency (JAXA)Sponsoring Organization
Information PendingResearch Benefits
Information PendingISS Expedition Duration:
April 2008 - September 2013Expeditions Assigned
17,18,19/20,25/26,27/28,29/30,31/32,33/34,35/36Previous ISS Missions
Increment 17 was the first mission for Marangoni.
Marangoni flow is categorized in the natural convection same as buoyancy convection caused by density difference. A trait of Marangoni convection is a surface-tension-driven flow which driving force is localized at the only surface. 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. One can see the coin floating on the water. Surface tension is the force to be keeping the heavier coin on. In general, surface tension becomes strong with decreasing temperature. When a temperature difference exists along surface, the surface is pulled toward low temperature region. The surface tension difference is also produced under existing concentration distribution. May have heard or seen "tears of wine". It can be caused by Marangoni effect under concentration difference near the meniscus. Its effect was named after Italian physicist Calro Marangoni who mainly studied surface phenomena in 19th century.
Such a phenomenon is often observed in everyday life. For example, oil in a pan heated from center moves to peripheral side. Oil floating on water immediately moves when a surfactant (e.g. detergent) drops onto a part of the oil because of the imbalance in the surface tension. The detergent caused the center to have a lower surface tension. On the other hand, the outside has a higher surface tension, so the center and the oil were pulled out in all directions to equalize the surface tension. These phenomena are resulting from Marangoni effect.
Moreover, Marangoni convection affects the quality of grown crystal such as semiconductors, optical materials or bio materials. Therefore, it is important to understand an underlying principal and nature of Marangoni convection. The finding and knowledge obtained through space experiment is applied to industrial progression as well as advance of fluid dynamics. A liquid bridge configuration is often employed to investigate Marangoni convection because it is simulated a floating-zone method which is one of the crystal growth technique.
A liquid bridge (cylindrical liquid column) of silicone oil is formed into a pair of supporting solid disks. The convection is induced by imposing the temperature difference between disks, one end heating and other end cooling. Due to the convective instability, flow transits from laminar to oscillatory, chaos, and turbulence flows one by ones as the driving force increases. Scientists will observe the flow and temperature fields in each stage and investigate the flow transition conditions and processes. Fundamental questions regarding to Marangoni Convection are as follows;
The valuable knowledge from Marangoni space experiment is also applicable to the high performance heat exchanger and heat pipe both in the space and on the earth. For future space development, it should be necessary to more efficient and compact thermal management system, no doubt to help its development.Earth Applications
The obtained knowledge on the Marangoni convection is vital for the production of high-quality crystal growth such as semiconductors, optical crystal so on. Since the surface tension is dominant not only under the microgravity but also in the micro-scale, the results obtained on the nature of the Marangoni convection will significantly contribute to various micro-fluid handling techniques in micro-TAS (Micro total analysis system) such as DNA examination and clinical diagnostics.
Number of experiment: 30 runs
Downlink of data: (Real-time)
As preparation for experiment by an ISS crew, the experiment cell is assembled and installed in FPEF. The experiment is operated from Space Station Integration and Promotion Center, Tsukuba Space Center by ground staffs.
The experiment procedure is as follows;
(1) Preparation of experiment
Warmer fluids move toward a cooler, higher surface tension region driven by a process known as thermocapillary force along the free (unbound) surface. Accordingly, convection is induced in fluid, which is called Marangoni convection. Depending on boundary conditions, the flow may be steady and symmetric or become unstable and time-dependent at a certain critical point. The Chaos, Turbulence and its Transition Process in Marangoni Convection (Marangoni-Exp) is designed to identify these critical conditions. In microgravity, scientists were able to form floating silicone oil columns much larger than on Earth allowing for a highly detailed observation of flow and instability within these "liquid bridges". A series of experiments have been carried out from 2008 ? 2013 in the Fluid Physics Experiment Facility (FPEF) of the ?KIBO? laboratory of the ISS.
Marangoni-Exps are set up with different oil viscosity and diameter. A series of experimental runs are changed the parameters such as temperature difference between supporting disks, and length for the liquid bridges, thus giving a wide range of aspect ratio (Ar = length over diameter) and volume ration for analysis. Convective flows are observed three-dimensionally by tracking fine tracer particles dispersed in the fluid and using CCD cameras at preset angles; an infrared (IR) camera is also used to see surface temperature distributions of the liquid bridge. Results show that, when critical temperature differences exceed a certain level, a standing-wave (imagine a horizontal liquid surface in a sealed half-filled glass jar tilting very slowly end to end) oscillation appears and that the wavelength is comparable to the length of the liquid bridge. The stable two-dimensional stationary flow pattern is replaced by the standing wave which then is followed by more chaotic flows with multiple vortices traveling from the heated zone toward the cooled zone. These results indicate that perturbations in the flow and temperature field are due to the propagation of simple and complex hydrothermal waves.
Critical temperature differences (?Tc), resultant Marangoni number (Mac), which is required for the onset of oscillatory flow, and oscillation frequency are determined for a wide range of aspect ratio and different fluid viscosities over the course of the Marangoni-Exp investigation. As expected, the measured ?Tc for the more viscous liquid is substantially higher than that for the less viscous one. Some of the experimental results are in good agreement with each other, while others show the similar patterns but are distinctly offset due, perhaps, to different fluid viscosity and the relative size of the liquid bridges (Yano et al., 2011, Kawamura et al., 2012).
Studying long liquid bridges in space will help scientists to make more accurate predictions of instability onsets which can give rise to different pattern forming instabilities. The floating-zone (liquid bridge) refining technique is used extensively to produce extremely high purity crystals by the semiconductor and rare metals industries, and flow disturbance is a major cause for the deterioration of the quality of the crystal grown by this method. Understanding the rheological (deformation and flow of matter) dynamics in liquid bridges is of fundamental interest for many industrial as well as biological processes.
Kawamura H, Nishino K, Matsumoto S, Ueno I. Report on Microgravity Experiments of Marangoni Convection Aboard International Space Station. Journal of Heat Transfer. 2012; 134(3): 031005-1 - 031005-13. DOI: 10.1115/1.4005145.
Goto M, Sakagami K, Matsumoto S, Ohkuma H. Entering "A NEW REALM" of KIBO Payload Operations - Continuous efforts for microgravity experiment environment and lessons learned from real time experiment operations in KIBO. Journal of Physics: Conference Series. 2011; 327(012054): 1-13. DOI: 10.1088/1742-6596/327/1/012054.
Yano T, Nishino K, Kawamura H, Ueno I, Matsumoto S, Ohnishi M, Yoda S. 3-D Flow Measurement of Oscillatory Thermocapillary Convection in Liquid Bridge in MEIS. Japan Society of Microgravity Application. 2011; 28(2): 126-132.
Yano T, Nishino K, Kawamura H, Ueno I, Matsumoto S, Ohnishi M, Sakurai M. 3-D PTV Measurement of Marangoni Convection in Liquid Bridge in Space Experiment. Experiments in Fluids. 2011; 53(1): 9-20. DOI: 10.1007/s00348-011-1136-9.
Yano T, Nishino K, Kawamura H, Ueno I, Matsumoto S, Ohnishi M, Sakurai M. Space Experiment on the Instability of Marangoni Convection in Large Liquid Bridge - MEIS-4: Effect of Prandtl Number -. Journal of Physics: Conference Series. 2011; 327. DOI: 10.1088/1742-6596/327/1/012029.
Kudo M, Shiomi J, Ueno I, Amberg G, Kawamura H. Experiment on multimode feedback control of non-linear thermocapillary convection in a half-zone liquid bridge. Advances in Space Research. 2005; 36(1): 57-63. DOI: 10.1016/j.asr.2005.05.046.
Ueno I, Tanaka S, Kawamura H. Oscillatory and Chaotic Thermocapillary Convection in a Half-Zone Liquid Bridge. Physics of Fluids. 2003; 15(2): 408-416. DOI: 10.1063/1.1531993.
Tanaka S, Kawamura H, Ueno I, Schwabe D. Flow structure and dynamic particle accumulation in thermocapillary convection in a liquid bridge. Physics of Fluids. 2006; 18(6): 067103-1 - 067103-11. DOI: 10.1063/1.2208289.