3 ms·

since two of the three methods of heat transfer (conduction and convection) This always drives me nuts. Convection is conduction, just in a fluid. Conduction

since two of the three methods of heat transfer (conduction and convection) This always drives me nuts. Convection is conduction, just in a fluid. Conduction and radiation are two entirely different physical processes.

zizee 5y ago
Doesn't convection also require movement of the fluid? Under gravity convection works by changes in density when the fluid is heated (e.g. hot air rises). This movement of the fluid provides an extra component beyond regular conduction. The movement of the fluid transfers heat away. In low g environments, convection due to density changes doesn't happen (hot air does not rise) which means heat pools around bodies at rest. Edit: after reading the article a bit, i see that you were quoting a section that ends with "...(conduction and convection) cannot occur without matter." Which does make the distinction the author was making a little more less useful. However lack of convection is an issue inside the space station where fans must be installed to keep air from pooling around heat sources like lights and human bodies.
guntars 5y ago
I think the distinguishing difference between conduction in a fluid and convection is that the fluid "leaves" and takes away the heat.
lmilcin 5y ago
Well, not exactly. Conduction means you touch something and that something slowly gets hotter and conducts heat away from your body. You can calculate how fast the energy is transferred based on properties of the material and geometry of objects and their interface. Convection means you touch something and that something is constantly being replaced. You can't use the formula for conduction here. In case of convection, the basic mechanism of energy being moved has nothing to do with conduction, rather with movement (replacement) of the material that takes away the heat. How is moving heat by moving the material and moving heat by letting it to dissipate through stationary material not two different processes?
only_as_i_fall 5y ago
Actually conduction is radiation at the atomic level. If you bring either point up in a conversation which is understood to be about macroscopic physics though you're really just being an ass.
- swiley 5y ago
  I thought conduction propagated as phonons rather than photons. But I guess the particle interaction comes from photon exchange, on the other hand the frequencies are different enough I think you can safely call it a different thing (like how UV and AM radio are different.)
- causality0 5y ago
  Thermal conduction is carried out with phonons and free electrons. It has a finite range. It is fundamentally distinct from thermal radiation which is propagated by photons with an infinite range.

zizee 5y ago

Doesn't convection also require movement of the fluid? Under gravity convection works by changes in density when the fluid is heated (e.g. hot air rises). This movement of the fluid provides an extra component beyond regular conduction. The movement of the fluid transfers heat away. In low g environments, convection due to density changes doesn't happen (hot air does not rise) which means heat pools around bodies at rest. Edit: after reading the article a bit, i see that you were quoting a section that ends with "...(conduction and convection) cannot occur without matter." Which does make the distinction the author was making a little more less useful. However lack of convection is an issue inside the space station where fans must be installed to keep air from pooling around heat sources like lights and human bodies.

guntars 5y ago

I think the distinguishing difference between conduction in a fluid and convection is that the fluid "leaves" and takes away the heat.

lmilcin 5y ago

Well, not exactly. Conduction means you touch something and that something slowly gets hotter and conducts heat away from your body. You can calculate how fast the energy is transferred based on properties of the material and geometry of objects and their interface. Convection means you touch something and that something is constantly being replaced. You can't use the formula for conduction here. In case of convection, the basic mechanism of energy being moved has nothing to do with conduction, rather with movement (replacement) of the material that takes away the heat. How is moving heat by moving the material and moving heat by letting it to dissipate through stationary material not two different processes?

only_as_i_fall 5y ago

Actually conduction is radiation at the atomic level. If you bring either point up in a conversation which is understood to be about macroscopic physics though you're really just being an ass.

swiley 5y ago
I thought conduction propagated as phonons rather than photons. But I guess the particle interaction comes from photon exchange, on the other hand the frequencies are different enough I think you can safely call it a different thing (like how UV and AM radio are different.)
causality0 5y ago
Thermal conduction is carried out with phonons and free electrons. It has a finite range. It is fundamentally distinct from thermal radiation which is propagated by photons with an infinite range.