Permanent Noncoalescence and Nonwetting:
Science and Applications

G. PAUL NEITZEL
George W. Woodruff School of Mechanical Engineering
Georgia Tech


Abstract:
Under the proper conditions it is possible to press together two drops of the same liquid without experiencing coalescence
or to press a liquid droplet against a surface normally wetted by the liquid without wetting occurring. By permanent
noncoalescence and nonwetting we distinguish cases in which the phenomena may be observed for unlimited time from
transient examples such as two drops of liquid bouncing off one another or a liquid droplet bouncing off a solid wall. To
achieve permanent noncoalescence or nonwetting, a mechanism is needed for establishing a lubricating film of surrounding
fluid (usually air) and sustaining this film as the liquid/liquid or solid/liquid surfaces are moved toward each other.

This talk will address means for the establishment of such lubricating films and discuss measurements and theory conducted
to understand the behavior of such systems. Finally, possible applications of permanent noncoalescence and nonwetting will
be described, including a demonstration of droplet levitation above a solid surface using non-contact, optical methods.