Entropy in the Brazil Nut Sorting Effect

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SUMMARY

The Brazil Nut effect, a phenomenon in granular convection, describes how larger grains rise to the surface while smaller grains sink, seemingly contradicting the second law of thermodynamics which states that entropy and multiplicity should increase. This discussion highlights the complexity of defining 'the system' in this context, particularly regarding energy states and the behavior of granular materials, which are often out of equilibrium. The conversation emphasizes that while entropy is typically a molecular-scale phenomenon, its implications can be observed in macroscopic systems like granular materials.

PREREQUISITES
  • Understanding of the second law of thermodynamics
  • Familiarity with granular materials and their behavior
  • Knowledge of potential energy concepts in physics
  • Basic principles of entropy and multiplicity in thermodynamic systems
NEXT STEPS
  • Research the implications of the second law of thermodynamics on macroscopic systems
  • Explore the dynamics of granular materials and their equilibrium states
  • Study potential energy and its role in packing and segregation of materials
  • Investigate the Brazil Nut effect in various granular systems beyond nuts
USEFUL FOR

Physicists, materials scientists, and anyone interested in thermodynamics and the behavior of granular materials will benefit from this discussion.

Tahmeed
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In Brazil Nut effect /Granular convection the large grains move upward and the smaller ones go downward. This sorting is supposed to reduce the multiplicity of this system. But according to the second law of thermodynamics, entropy and multiplicity of the system should increase.

I am looking for a detailed and intuitive explanation of this.
 
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Consider what you define as 'the system'. Does it have a fixed energy ?
 
Entropy is a molecular scale phenomenon. It is not expected to apply to macroscopic systems, such as how you organize your library (or how Brazil nuts gravitationally segregate).
 
Tahmeed said:
I am looking for a detailed and intuitive explanation of this.
Google is your friend. There's a lot behind pay walls, but I liked browsing this one, so: thanks for bringing it up !
BvU said:
Consider what you define as 'the system'. Does it have a fixed energy ?
My reason for putting it this way: I figured potential energy is won when interstitial void is reduced (closer packing). This energy is dissipated and can't be reconverted. But Chet's comment is quite valid although my own library definitely obeys the second law.

Page 211 in the link said:
granular materials are a system out of equilibrium at almost any level
 

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