Capillarity effects on surface gravity waves in a cylindrical container: wetting boundary conditions

Surface capillary–gravity waves are experimentally investigated in a cylindrical basin subjected to a horizontal oscillation by using a high-sensitivity optical method. We study the low-oscillation-amplitude regimes for a fluid which wets the vertical walls and we show that the presence of the capillary meniscus can effect greatly the main properties of the system. Both the free decay and the forced oscillations of surface oscillations are investigated. The amplitude, the phase and the damping of gravity waves are investigated in detail. The damping of the fundamental surface mode is found to exhibit nonlinear behaviour which is in qualitative agreement with the predictions of the Miles (1967) theory of capillary damping. The amplitude and the phase of gravity waves with respect to the oscillation of the container exhibit unusual behaviour which is strictly connected with the presence of the wetting boundary condition for the fluid at the vertical walls.