Basic Mechanisms in Aerosol Production

Abstract

The production of capillary waves and aerosols has been examined to gain some insight into the rôle played by capillary waves in the production of aerosol. Vibration-amplitude measurements have been made which suggest two things. First, viscosity is an important factor in the thresholds for the formation of capillary waves and for the production of aerosol. Second, at the threshold for the production of aerosol, one is exciting the second as well as the first unstable solution zone of Mathieu's equation, the controlling equation for capillary waves. The wavelengths in these two zones are nonintegrally related and it is proposed that this fact is basic to the production of aerosol. Cavitation effects are also observed to be present. In liquids with large viscosity indices, such as castor oil, capillary waves are not observed; one sees only the cavitation effects. It is suggested, then, that the basic controlling mechanism (capillary waves or cavitation) is determined by which threshold is reached first as one increases the vibration amplitude. [Work sponsored in part by U. S. Army, Edgewood Arsenal, Maryland.]