Why do fluid drops are sperical?

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In summary, The conversation discusses the shape of fluid drops in air and the role of surface tension in maintaining their spherical shape. The question is raised about why the drops are not ellipsoidal due to the pressure of the air on everything submerged in it. The response explains that surface tension balances the aerodynamic forces and mostly wins, resulting in spherical drops. The conversation then delves into the potential shape of drops in different materials and environments.
  • #1
fluidistic
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Hi,
I'm almost sure that this question frequently appears and have been asked thousands of times and if so, then excuse me and I'll be OK if you give me a link to such a thread.
I don't understand why fluid drops in air are not ellipsoidal since the air makes pressure vertically on everything submerged in it. The same apply for air's bubbles in water. Water makes pressure vertically and so the bubble should get an ellipsoidal form, but it doesn't.
Thank you!
 
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  • #2
Surface tension balances the aerodynamic forces - mostly surface tension wins so the drops are almost spherical.
 
  • #3
mgb_phys said:
Surface tension balances the aerodynamic forces - mostly surface tension wins so the drops are almost spherical.

Thanks SO much!
If I find a fluid that has a little surface tension and I put it say in deep ocean (more than 10km under water surface) then I'd likely get an ellipsoidal bubble. :smile: if I understand well.
 
  • #4
Well there is still the surface tension of the water because there is a surface around the bubble.
It would be interesting to know what shape 'raindrops' of other materials formed in air - say organic solvents or superfluid helium!
 

FAQ: Why do fluid drops are sperical?

1. Why are fluid drops spherical?

Fluid drops are spherical because of a phenomenon called surface tension. Surface tension is the result of cohesive forces between molecules in a liquid, which causes the liquid to minimize its surface area. In the case of a drop, this means that the liquid will form a shape with the least possible surface area, which is a sphere.

2. How does surface tension contribute to the spherical shape of fluid drops?

Surface tension is the force that pulls the molecules of a liquid toward the center of the drop, creating a uniform pressure on all sides. This pressure causes the liquid to maintain a spherical shape, as it is the shape with the least amount of surface area for a given volume.

3. Can fluid drops be any other shape besides spherical?

In most cases, fluid drops will naturally form a spherical shape due to surface tension. However, if there are external forces acting on the drop, such as gravity or air resistance, the drop may take on a different shape. Additionally, certain liquids with different surface tensions may form non-spherical shapes as well.

4. Why do fluid drops form a spherical shape even when placed on a flat surface?

When a fluid drop is placed on a flat surface, the surface tension of the liquid will pull the molecules towards the center of the drop, causing it to maintain a spherical shape. The flat surface may slightly deform the shape of the drop, but it will still remain mostly spherical due to the cohesive forces within the liquid.

5. Is the spherical shape of fluid drops affected by temperature?

Yes, the temperature of the liquid can affect the surface tension and therefore the shape of fluid drops. As temperature increases, the surface tension of the liquid decreases, which can result in a less spherical shape. This is why drops of water on a hot surface may flatten out and appear less spherical.

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