•  Thermophoresis: Particle motion in a temperature gradient, from a hotter to a colder region

 

Molecular impacts on a particle

(dp < l) in a temperature gradient

 

Free Molecular Regime

•  Thermal force on a particle

 

 

 

 

 

Continuum Regime

· Thermal force on a particle

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

and l is the mean free path, ka, kp are the thermal conductivity  of gas and particle.

Motion of particles (thermophoresis)