CAPILLARY PHENOMENA .7. EQUILIBRIUM AND STABILITY OF PENDENT DROPS

The behavior is described of pendent drops beneath tips of radius XΘ, and beneath horizontal plates where the contact angle is θ. The treatment of the equilibrium and stability is largely based on the computation of meridian curves satisfying either of these boundary conditions. Novel phenomena which are thought to be physically realizable are predicted. Features described include volume maxima for the two boundary conditions, and complications which can arise with tips; pressure maxima for constant contact radius XΘ, but not when the radius varies and θ remains constant; the determination of the residual drop volume following detachment; the use of drop heights, especially since the maximum height occurs in an unstable region; and the implications for interfacial tension determination techniques. The mechanical requirements of systems with which the various instabilities could be detected are described; they are briefly referred to as involving stress control or strain control with a piston arrangement. © 1978.