diffusion
Let an agent explain diffusion by mechanism, equations, examples in physics, chemistry and biology, and separate figurative senses such as diffusion of innovations.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain diffusion by mechanism, equations, examples in physics, chemistry and biology, and separate figurative senses such as diffusion of innovations.
The net movement of particles, molecules or other quantities from regions of higher concentration to regions of lower concentration driven by random motion, described by Fick laws; related transport includes osmosis, and the term is also used for heat, momentum and the spread of ideas.
What it is for: Understanding transport in materials, cells and the environment.
It can be explain diffusion and Fick laws; estimate diffusion times and coefficients; describe diffusion in cells and lungs; separate social diffusion senses.
Distinguishing features
Driven by random motion
Down a concentration gradient
Slow over long distances
Described by Fick laws
What it looks like
Not directly visible; seen as spreading dye, smells or gradients.
Physical character
typical diffusion coefficient of small molecules in water: about 1e-9 m2/s - order of magnitude
How it is recognised
Dye spreading in still water
Concentration gradients
Convection moves bulk fluid rather than individual particles
Related models
is a kind of - category
is described by - law
includes - related process
is related to - mechanism
In practice
Families and kinds
molecular diffusion
osmosis
facilitated diffusion across membranes
diffusion in solids
turbulent and eddy diffusion
Standards and regulation
No specific regulation; test standards exist for diffusion in materials
Failure modes and hazards
Confusing diffusion with convection
Ignoring temperature dependence
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.diffusion
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Mechanism How it works.
Random motion drives it.
Random
Brownian motion.
Random
Random motion.
- How does random molecular motion produce net diffusion? definition
- How does temperature affect it? definition
Fick
Laws.
Fick
Fick laws.
- How do Fick first and second laws describe the flux? definition
- What is the diffusion coefficient here? measurement
Estimation Numbers.
Scales matter.
Time
Diffusion time.
Time
Diffusion time.
- How long does diffusion take over this distance? measurement
- Why does time scale with distance squared? definition
Data
Coefficients.
Data
Coefficient data.
- What is the tabulated diffusion coefficient for this substance and medium? provenance
- At what temperature? measurement
Biology Living systems.
Cells rely on diffusion.
Cells
Membranes.
Cells
Membrane transport.
- How do substances diffuse across cell membranes? definition
- When is a transporter needed? boundary
Lungs
Gas exchange.
Lungs
Gas exchange.
- How does gas exchange in the lungs rely on diffusion? definition
- What affects its rate? definition
Senses Disambiguation.
Diffusion has other senses.
Social
Innovations.
Social
Social sense.
- Is the diffusion of innovations or cultural diffusion meant? boundary
- Which entry fits? action
AI
Diffusion models.
AI
Machine learning sense.
- Is a diffusion model in machine learning meant? boundary
- Which entry fits? action
What the second pass must settle
- Should kinds of diffusion be separate entries?
- How should coefficient data be linked?
- How should social diffusion be split off?