  We present the results of an experimental investigation on parametrically
driven waves in a water half-cylinder on a rigid horizontal plate, which is
sinusoidally vibrated in the vertical direction. As the forcing amplitude is
raised above a critical value, stationary waves are excited in the water
half-cylinder. Parametrically excited subharmonic waves are non-axisymmetricand
qualitatively different from the axisymmetric Savart-Plateau-Rayleigh waves in
a vertical liquid cylinder or jet. Depending on the driving frequency,
stationary waves of different azimuthal wave numbers are excited. A linear
theory is also supplemented, which captures the observed dispersion relations
quantitatively.
