Quantitative experimental observation of weak inertial-wave turbulence

Eduardo Monsalve

We report on experiments of rotating wave-turbulence. In the first part, a set of wavemakers produces inertial-wave beams, which interact in the center of a water tank mounted on a rotating platform. For moderate forcing amplitude, part of the energy of the waves is transferred to subharmonic, through a typical triadic resonance instability. However, stronger forcing condenses the energy into a vertical geostrophic flow, preventing the wave turbulence regime. In the second part, we add rough top and bottom boundaries. In this case, we prevent the emergence of a geostrophic flow, leading to a statistically steady homogeneous turbulent flow where most of the energy is carried by waves. When we increase the forcing amplitude, the temporal spectrum and the map of bicoherence evolve from a discrete set of peaks to a continuous spectrum. The spatial spectra then display a power-law behavior, both the spectral exponent and the spectral level being predicted by wave turbulence theory.

Related paper: https://arxiv.org/abs/2010.15563