Would an unstable emulsion separate in the abscense of gravity? How?

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SUMMARY

The discussion centers on the behavior of unstable emulsions, specifically the separation of water and oil in the absence of gravity. Participants assert that while gravity typically causes lower density liquids to rise, in a microgravity environment, surface tension and cohesive forces between water molecules play a crucial role in determining the layering structure. It is concluded that smaller droplets may segregate due to cohesive attraction, while larger volumes may not exhibit noticeable separation due to their scale and lack of interaction. The potential for very slow coalescence and segregation over extended periods is also acknowledged.

PREREQUISITES
  • Understanding of emulsion stability and phase separation
  • Knowledge of surface tension and its effects on liquid behavior
  • Familiarity with Brownian motion and its implications for small particles
  • Basic principles of fluid dynamics in varying gravitational conditions
NEXT STEPS
  • Research the effects of surface tension on emulsion stability in microgravity environments
  • Explore the principles of Brownian motion and its role in particle coalescence
  • Investigate the dynamics of phase separation in various liquid mixtures
  • Study the impact of cohesive forces in liquid interactions and their implications for emulsion behavior
USEFUL FOR

Researchers in fluid dynamics, chemists studying emulsions, and physicists interested in the behavior of liquids in microgravity environments will benefit from this discussion.

thermodragon
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TL;DR
If you have two different liquids (water and oil for example) mixed together and free floating without gravity, will they separate as they do here on Earth? If so, what property would determine the layering structure?
If you have two different liquids (water and oil for example) mixed together and free floating without gravity, will they separate as they do here on Earth? If so, what property would determine the layering structure? I suspect they would separate, and if left undisturbed probably form a spherical layered structure. But which liquid would be on the outside and which would be on the inside? In the presence of gravity, the lower density liquid would lie on top, but in the absence of gravity is it a function of surface tension? Or some other property(ies)?
 
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Who says they will separate into a layered structure? Why wouldn't the oil just form globules without globally coalescing?
 
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I'm unsure. I suppose this can't be the case for large amounts of liquid. I imagine if you had a blob of 1 m^3 of water and two little drops of oil on either side, they wouldn't have any way of even knowing about each other. For smaller drops though, I was thinking the cohesive attraction between water molecules would squeeze the oil out of its way and make it energetically favorable to segregate the two liquids completely.
 
thermodragon said:
I'm unsure. I suppose this can't be the case for large amounts of liquid. I imagine if you had a blob of 1 m^3 of water and two little drops of oil on either side, they wouldn't have any way of even knowing about each other. For smaller drops though, I was thinking the cohesive attraction between water molecules would squeeze the oil out of its way and make it energetically favorable to segregate the two liquids completely.
I'm unsure also, but it seems to me that the cohesive attraction between water molecules has already been satisfied by the occurrence of the phase separation. But maybe self-gravitation of the fluids could contribute to very very slow coalescence and segregation over very a long period of time.
 
If there are many small oil droplets with a short distance between them, they can also reach each other by Brownian motion and form larger blobs.
 
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