INTERACTION OF EVAPORATING AND CONDENSING PARTICLES IN THE FREE-MOLECULAR REGIME

In a previous paper it was shown that repulsive/attractive forces aris e between evaporating/ condensing particles in the free-molecular regi me. Here we obtain explicit expressions for these forces in the case o f spherical particles with equal temperatures. The temperature of the surrounding vapor is, generally speaking, different from that of the p articles. Numerical results are obtained for different values of the r atios between particle and vapor temperatures and pressures, of the pa rticles radii and of the evaporation coefficients. In the case when th e evaporation coefficient equals unity, an exact expression is obtaine d for the force between particles of different radii. A simple model d escribing coagulation processes and taking the above-mentioned forces into account is proposed. It is shown that for large values of the vap or supersaturation, the influence of these forces on the coagulation r ate may be very pronounced. (C) 1995 American Institute of Physics.