Entropy of Diffusion: Delta Initial Condition

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SUMMARY

The discussion centers on calculating the entropy of a diffusion constant as a function of time, specifically using a delta initial condition. The entropy is defined by the equation S = k p ln p, where p represents the probability density function derived from the diffusion kernel. The challenge lies in integrating this entropy definition over space, particularly with the natural logarithm term. The problem involves a heat equation without a source term and an open boundary condition at infinity.

PREREQUISITES
  • Understanding of entropy in statistical mechanics
  • Familiarity with diffusion processes and diffusion coefficients
  • Knowledge of integral calculus, particularly in multiple dimensions
  • Experience with heat equations and boundary conditions
NEXT STEPS
  • Research the derivation of entropy in diffusion processes
  • Study the application of the diffusion kernel in statistical mechanics
  • Learn about integrating probability density functions over spatial domains
  • Explore the implications of open boundary conditions in diffusion equations
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Students and researchers in physics, particularly those focusing on thermodynamics, statistical mechanics, and diffusion processes. This discussion is also beneficial for anyone involved in mathematical modeling of physical systems.

simoncks
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Homework Statement


The problem requires me to find the entropy of a diffusion constant as a function of time (I guess in terms of diffusion coefficient)

Homework Equations


Perhaps Heat / Diffusion kernel
S = k p lnp

The Attempt at a Solution


I assume it was a delta initial condition then apply the kernel. However I need to turn the entropy definition into an integral over space. The kernel times differential volume is the probability finding the particle in that space but the natural log term is tricky.
 
In short, I would like to know if there are any entropy equation integrating over space.
 
You are asking what entropy S is produced by time t by diffusion through a medium characterized by diffusion coefficient D_{ij}? If so, could you indicate the arrangement of the system at t = 0; is a point-source diffusing?
 
It is a heat equation without source term. Open boundary at infinity. Initial condition is a delta function at (x,y,z) = 0.
 

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