Thermal diffusion

Thermal diffusion may refer to: A thermal force on a gas due to a temperature gradient, also called thermal diffusion or Thermal transpiration. It is used to drive a gas pump with no moving parts called a Knudsen pump. It is the currently accepted theory for the rotation of the Crookes radiometer. Diffusion in a temperature gradient, also called thermodiffusion or thermophoresis. It can be used as an obsolete method of making enriched uranium (see enriched uranium § thermal diffusion). Thermal diffusion can be used to measure fluid flow, including perfusion and rCBF at one location over time. Brownian motion (at a constant non-zero absolute temperature). See also: Molecular diffusion Heat conduction (i.e., diffusion of heat)