> C. Ruyer-Quil
On the Kapitza instability and the generation of capillary waves
Georg Dietze (FAST)
The classical problem of a liquid film falling along a vertical
wall due to the action of gravity is revisited. The free-surface of such a
flow is typically deformed into a train of solitary pulses that consists
of large asymmetric wave humps preceded by small precursory ripples,
designated as "capillary waves". We set out to answer four fundamental
questions: (i) By what mechanism do the precursory ripples form? (ii) How
can they travel at the same celerity as the large-amplitude main humps?
(iii) Why should they be designated as "capillary waves"? (iv) What
determines their wavelength and number and why do they attenuate in space?