DTIC ADA280187: Marangoni Convection in a Gravity pdf

DTIC ADA280187: Marangoni Convection in a Gravity

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The onset of Marangoni convection in the float zone of liquid silicon is studied from a state at rest in the absence of gravity. This time-dependent flow problem is solved numerically with the aid of the Navier-Stokes equations for an axisymmetric flow with nonlinear free surface conditions. On this free surface the temperature gradient is generated by heat transfer and radiation from a heater, which is symmetrically located between the two walls of the float zone. After a certain time, the flow is asymmetrically disturbed by moving the heater for a short time away from its symmetric position and back. Three different Marangoni numbers (based on the temperature difference between heater and melting point of silicon) are computed: 10,400, 30,225, and 50,050. The results show that for Ma = 10,400 the flow is steady and stable. For the two higher Marangoni numbers, however, the disturbed flows become unstable, and persistent oscillatory modes of 0.22 Hz for Ma = 30,225 and 0.27 Hz for Ma = 50, 050 develop.

Silicon float zone, Marangoni convection

• Creator/s: Defense Technical Information Center
• Date: 4/1/1994
• Year: 1994
• Book Topics/Themes: DTIC Archive, Lugt, Hans J, NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD, *REGIONS, *FLOATS, *GRAVITY, *SURFACE TENSION, *SILICON, HEAT TRANSFER, RADIATION, TIME DEPENDENCE, NUMBERS, OSCILLATION, CAPILLARY WAVES, AXISYMMETRIC FLOW, HEATERS, FLUID MECHANICS, REST, MELTING POINT, NAVIER STOKES EQUATIONS, WALLS, SURFACE PROPERTIES, TEMPERATURE GRADIENTS, LIQUIDS, CONVECTION, CRYSTALS

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