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Thermocapillary Convection Space Experiment on the SJ-10 Recoverable Satellite
Published on: March 11, 2020
Double-layer thermocapillary convection in a differentially heated cavity
Nivedita R Gupta1, Hossein Haj-Hariri, Ali Borhan
1Department of Chemical Engineering, University of New Hampshire, Durham, New Hampshire 03824, USA.
Annals of the New York Academy of Sciences
|November 25, 2006
Summary
Encapsulant layers in microgravity crystal growth alter thermocapillary flows. Higher encapsulant viscosity reduces melt convection but weakens the free surface
Area of Science:
- Materials Science
- Fluid Dynamics
- Microgravity Science
Background:
- Thermocapillary flows impact materials processing, especially in microgravity.
- Encapsulant layers are used for volatile melts (e.g., III-V semiconductors) to prevent evaporation.
- Encapsulant interfaces can significantly alter melt thermocapillary convection.
Purpose of the Study:
- Investigate thermocapillary convection in a two-immiscible-liquid system under microgravity.
- Analyze the effect of a deformable melt-encapsulant interface on flow dynamics.
- Compare results with a rigid top surface scenario.
Main Methods:
- Numerical simulation of a differentially heated rectangular cavity with two immiscible liquid layers.
- Utilized domain mapping and a finite difference scheme on a staggered grid.
- Allowed deformation of melt-encapsulant and air-encapsulant interfaces with pinned contact lines.
Main Results:
- A free surface at the top increased convection in the encapsulant but suppressed melt thermocapillary flow.
- Encapsulant layer viscosity strongly influenced the flow pattern.
- Increased encapsulant viscosity reduced melt thermocapillary flow intensity, but weakened the free surface's retarding effect at higher viscosities.
Conclusions:
- The presence and properties of an encapsulant layer, including its viscosity and interface deformability, critically affect thermocapillary convection in microgravity materials processing.
- Understanding these complex interactions is crucial for optimizing crystal growth and materials quality.
- Numerical modeling provides valuable insights into these phenomena, aiding in process design and control.
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