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Shape relaxation of liquid drops in a microgravity environment
S S Sadhal1, A Rednikov, K Ohsaka
1University of Southern California, Los Angeles, CA 90089-1453, USA. sadhal@usc.edu
Annals of the New York Academy of Sciences
|January 13, 2005
Summary
Liquid drops in microgravity relax to a spherical shape. A model accurately predicts this for acoustically levitated drops but is less successful for electrostatically levitated drops due to conductivity effects.
Area of Science:
- Fluid dynamics
- Surface tension phenomena
- Microgravity experiments
Background:
- Liquid drops deform under combined forces like levitation, surface tension, and gravity.
- Microgravity allows studying shape relaxation driven solely by surface tension.
- Acoustic/electrostatic hybrid levitators are used to manipulate liquid samples.
Purpose of the Study:
- To investigate the shape relaxation dynamics of liquid drops in microgravity.
- To compare experimental shape relaxation data with a theoretical linear relaxation model.
- To identify factors influencing the accuracy of the relaxation model.
Main Methods:
- Generating microgravity by free fall of levitated liquid drops.
- Using an acoustic/electrostatic hybrid levitator for initial drop suspension.
- Measuring drop aspect ratio over time to quantify shape relaxation.
- Comparing experimental data to a linear relaxation model for perfectly conductive drops.
Main Results:
- Deformed liquid drops restored a spherical shape during free fall, driven by surface tension.
- The linear relaxation model adequately described shape relaxation for uncharged/charged drops from acoustic levitation.
- The model showed less success for drops initially levitated electrostatically.
Conclusions:
- Surface tension is the primary driver for shape relaxation to a spherical form in microgravity.
- The linear relaxation model is effective for acoustically levitated drops but needs refinement for electrostatically levitated ones.
- Finite electrical conductivity of liquids likely impacts the initial stages of shape relaxation in electrostatically levitated drops.
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