Spatio-temporal Flow Structure in Marangoni Convection

For a comprehensive understanding of a flow phenomenon in a floating zone crystal melt, liquid column Marangoni convection will be investigated under microgravity, using silicone oil as working fluids with their viscosity levels changed. Flow measurement of Marangoni convection will be carried out by the Ultrasonic Velocity Profile(UVP) method based on the Doppler effect and by the optical measurement method as well. The effect of controlling parameters of Marangoni convection such as Marangoni number, Grashof number and Prandtl number, on the flow behavior will be studied. A combined analysis of the experimental results, both by UVP and optical methods, is expected to lead to a basic understanding of the flow phenomenon in the floating zone crystal melt and an establishment of its theoretical modeling.

Chaos, Turbulence and its Transition Process in Marangoni Convection

The Marangoni convection is a hydrodynamic phenomena which is prominent in the material production under the reduced gravity. The material production under the reduced gravity is influenced by the Marangoni convection significantly. In the present experiment, a liquid bridge is formed and a temperature difference is imposed between the both end surfaces. The resultant Marangoni convection is measured with use of the three-dimensional particle-tracking velocimetry. The transition to periodic, chaotic and turbulent flows are investigated experimentally. The spectrum of fluctuations and the distribution of turbulent energy are measured. Further, effects of the liquid bridge shape on the transition phenomena and flow state of Marangoni convection is also examined. Numerical simulations are performed in parallel and are compared with the experimental results.