Thermophoresis in sols.

Experiments were conducted on the motion of micron-size, spherical latex particles in stagnant liquids due to applied temperature gradients. The phenomenon, called thermophoresis, has previously been reported for gases but not for liquids. Dilute suspensions of particles in water or n-hexane were trapped between two horizontal, parallel disks. The top disk was heated whereas the lower one was cooled, thus creating a temperature gradient in the liquid. The particle motion was measured by observing light reflected from the spheres with a low power microscope. The particle thermophoretic velocity, vth, was found to be a function of temperature gradient, ▽T, absolute temperature, TK, particle thermal conductivity, kp , fluid thermal conductivity, kf, viscosity, μ, and density, ρ: [ Formula omitted ] This equation was tested in the ranges 284 °K <_ TK <_ 343 °K and 7,000 °K m ̄¹ <_ ▽T