Meniscus instability in a thin elastic film

A new kind of meniscus instability leading to the formation of stationary f ingers with a well-defined spacing has been observed in experiments with el astomeric films confined between a plane rigid glass and a thin curved glas s plate. The wavelength of the instability increases linearly with the thic kness of the confined film, but it is remarkably insensitive to the complia nce and the energetics of the system. However, lateral amplitude (length) o f the fingers depends on the compliance of the system and on the radius of curvature of the glass plate. A simple linear stability analysis is used to explain the underlying physics and the key observed features of the instab ility.