Astrophysics (Index)About

diffusion

(the spreading of particles toward an even distribution)

Diffusion is the net movement of particles such as atoms or molecules from areas of higher concentration to areas of lower concentration. If there is some random particle motion within a fluid producing random walks, diffusion occurs. A diffusion equation is an equation describing diffusion over time. Fick's laws include a diffusion equation describing what happens in many cases, a type of diffusion termed Fickian diffusion. The equation:

       dC
J = -D ——
       dx

Amount of substance is a measure of the number of particles (atoms or molecules) of the substance typically counted in moles


(physics,chemistry)
Further reading:
https://en.wikipedia.org/wiki/Diffusion
https://en.wikipedia.org/wiki/Fick%27s_laws_of_diffusion
http://mathbench.umd.edu/modules/cell-processes_diffusion/page09.htm
https://serc.carleton.edu/NAGTWorkshops/mineralogy/mineral_physics/diffusion.html

Referenced by pages:
atmospheric escape
diffusion damping
Eddington approximation
radiation zone
stellar evolution
two-stream approximation

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