Vol. 28, issue 02, article # 4

Abstract:

The role of accommodation coefficients of energy and tangential and normal momenta in the phenomenon of thermophoresis of a spherical aerosol particle in the Knudsen (free-molecular) mode was studied. Feature of this work is that it does not use any assumptions about the distribution function of the gas molecules reflected from the surface of particles. Accommodation coefficients are introduced into the equations directly through the momentum and energy fluxes.
The expressions for the force and rate of thermophoresis, as well as for thermal polarization of particles (the difference in temperatures at diametrically opposite points on the particle surface in the direction of incoming flow of gas) were obtained. It was shown that in the Knudsen mode the force and rate of thermophoresis depend only on the accommodation coefficient of momentum, and do not depend on the accommodation coefficient of energy. The value of thermal polarization, on the contrary, is directly proportional to the accommodation coefficient of energy, but does not depend on the accommodation coefficient of momentum.

Keywords:

thermophoresis, accommodation coefficients of energy and momentum, thermal polarization of the aerosol particle, gas, molecule

References:

1. Fuks N.A. Mehanika ajerozolej. M.: Izdatelstvo AN SSSR, 1955. 352 p.
2. Bakanov S.P., Derjagin B.V. O teorii termoprecipitacii vysokodispersnyh ajerozol'nyh sistem // Kolloid. zh. 1959. V. 21, N 4. P. 377–384.
3. Brock J.R. The thermal force in the transition region // J. Colloid  Interface Sci. 1967. V. 23, N 3. P. 448–452.
4. Beresnev S.A., Chernyak V.G. Thermophoresis of a spherical particle in a rarefied gas: Numerical analysis based on the model kinetic equations // Phys. Fluids. 1995. V. 7, N 7. P. 1743–1756.
5. Ferciger Dzh., Kaper G. Matematicheskaja teorija processov perenosa v gazah. M.: Mir, 1976. 554 p.