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J M Burgess1, A Juel, W D McCormick
1Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
Physical Review Letters
|February 15, 2001
Summary
Gravitationally unstable liquid layers can be stabilized by thermocapillarity. A critical temperature difference prevents instability, with the most unstable wavelength becoming infinitely long at this point.
Area of Science:
- Fluid dynamics
- Surface physics
Background:
- Isothermal liquid layers suspended from a surface are inherently unstable due to gravity (Rayleigh-Taylor instability).
- Temperature gradients can influence fluid behavior through surface tension effects (thermocapillarity).
Purpose of the Study:
- To investigate the stabilizing effect of thermocapillarity on gravitationally unstable liquid layers.
- To determine the critical temperature difference required for stabilization.
- To analyze the relationship between temperature difference and instability wavelengths.
Main Methods:
- Experimental measurements of the most unstable wave number.
- Linear stability analysis of the liquid-gas layer system.
- Imposing a vertical temperature difference across the layer, heated from below.
Main Results:
- A vertical temperature difference above a critical value, (DeltaT)(c), stabilizes the liquid layer.
- The stabilizing force is provided by temperature-dependent surface tension (thermocapillarity).
- Experimental measurements for DeltaT < (DeltaT)(c) align with linear stability predictions.
- The instability manifests at long wavelengths, with the most unstable wavelength approaching infinity at (DeltaT)(c).
Conclusions:
- Thermocapillarity can effectively counteract gravitational instability in suspended liquid layers.
- The critical temperature difference is a key parameter for controlling layer stability.
- Instability onset is characterized by a transition to infinite wavelengths.