The damping rates, natural frequencies and amplitudes of parametrically
excited,
standing, water waves in a partially filled, right circular cylinder are
measured and
compared to existing theoretical models that assume wave slopes are small.
The water
surfaces were covered by insoluble monomolecular (surfactant) films of
oleyl alcohol,
lecithin, diolein, cholesterol, and arachidyl alcohol whose concentrations
were varied
from zero (clean) to saturation; wave slopes were varied from about 0.1
to 1.2.
Measured damping rates increased with increasing film concentration as
predicted
using films of oleyl alcohol, lecithin, and diolein, even when wave slopes
were about
one. Measured damping rates increased with increasing film concentration
as predicted,
using films of cholesterol and arachidyl alcohol when wave slopes were
small, but not
when wave slopes were large. In fact, the measured damping rates for large-slope
waves on these films were equivalent to those of waves on a clean surface.
Measured
natural frequencies varied as predicted for all films, but were about 5%
larger.
Contact-line effects are incorporated, using an empirical value for contact-line
speed,
to account for discrepancies between measurements and predictions of damping
rates
and natural frequencies. Measured steady-state amplitudes agreed well with
predictions
that used measured damping rates and natural frequencies in the calculations
for all
films except lecithin and arachidyl alcohol for which there was significant
disagreement.