PARTICLE-TRANSPORT AT SUBATMOSPHERIC PRESSURES - MODELS AND VERIFICATION

This paper reports on a program comparing calculated and experimental values of particle deposition velocity at pressures down to 100 pascal s (1 millibar). The calculated values were obtained by incorporating t he pressure dependence of gas density and the Cunningham slip correcti on factor into previously published particle deposition models. While the deposition mechanisms modeled included sedimentation, diffusion, t hermophoresis, electrophoresis, and photophoresis, experimental measur ements have been made so far to verify only the sedimentation model. T he experimental results presented confirm the predicted increased impo rtance,of gravitational settling at subatmospheric pressures.