1,181 research outputs found
Observation of resonant interactions among surface gravity waves
We experimentally study resonant interactions of oblique surface gravity
waves in a large basin. Our results strongly extend previous experimental
results performed mainly for perpendicular or collinear wave trains. We
generate two oblique waves crossing at an acute angle, while we control their
frequency ratio, steepnesses and directions. These mother waves mutually
interact and give birth to a resonant wave whose properties (growth rate,
resonant response curve and phase locking) are fully characterized. All our
experimental results are found in good quantitative agreement with four-wave
interaction theory with no fitting parameter. Off-resonance experiments are
also reported and the relevant theoretical analysis is conducted and validated.Comment: 11 pages, 7 figure
Observation of gravity-capillary wave turbulence
We report the observation of the cross-over between gravity and capillary
wave turbulence on the surface of mercury. The probability density functions of
the turbulent wave height are found to be asymmetric and thus non Gaussian. The
surface wave height displays power-law spectra in both regimes. In the
capillary region, the exponent is in fair agreement with weak turbulence
theory. In the gravity region, it depends on the forcing parameters. This can
be related to the finite size of the container. In addition, the scaling of
those spectra with the mean energy flux is found in disagreement with weak
turbulence theory for both regimes
Observation of intermittency in wave turbulence
We report the observation of intermittency in gravity-capillary wave
turbulence on the surface of mercury. We measure the temporal fluctuations of
surface wave amplitude at a given location. We show that the shape of the
probability density function of the local slope increments of the surface waves
strongly changes across the time scales. The related structure functions and
the flatness are found to be power laws of the time scale on more than one
decade. The exponents of these power laws increase nonlinearly with the order
of the structure function. All these observations show the intermittent nature
of the increments of the local slope in wave turbulence. We discuss the
possible origin of this intermittency.Comment: new version to Phys. Rev. Let
Additive Noise Induces Front Propagation
The propagation of a front connecting a stable homogeneous state with a
stable periodic state in the presence of additive noise is studied. The mean
velocity was computed both numerically and analitically. The numerics are in
good agreement with the analitical prediction.Comment: 4 pages, 5 figure
Axisymmetric solitary waves on the surface of a ferrofluid
We report the first observation of axisymmetric solitary waves on the surface
of a cylindrical magnetic fluid layer surrounding a current-carrying metallic
tube. According to the ratio between the magnetic and capillary forces, both
elevation and depression solitary waves are observed with profiles in good
agreement with theoretical predictions based on the magnetic analogue of the
Korteweg-deVries equation. We also report the first measurements of the
velocity and the dispersion relation of axisymmetric linear waves propagating
on the cylindrical ferrofluid layer that are found in good agreement with
theoretical predictions.Comment: to be published in Phys. Rev. Let
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