SURFACE-TENSION RESTORING FORCES ON GRAVITY-WAVES IN NARROW CHANNELS

Surface tension restoring forces are investigated for low amplitude gravity waves propagating in narrow channels. Liquids which do not wet the container walls experience a nonuniform displacement of the meniscus as the wave passes. The variation of surface curvature leads to a surface tension force which increases the velocity of the gravity wave. The effect is substantial in experiments with water in Plexiglass channels. The dependence on channel width and contact angle has been investigated, and agreement is found with a simple theoretical model. Addition of a wetting agent to the water eliminates the effect, decreasing the velocity to within 1% of the classical dispersion relation. © 1979 American Institute of Physics.