Capillary wave turbulence on a spherical fluid surface in low gravity

TL;DR

This study observes capillary wave turbulence on a spherical fluid surface in low gravity, revealing power-law spectra and spherical patterns, advancing understanding of wave behavior without gravity influence.

Contribution

It demonstrates the first large-scale observation of capillary wave turbulence on a spherical surface in low gravity, aligning with wave turbulence theory.

Findings

Power-law spectrum over two decades in frequency

Observation of spherical patterns like stripes and hexagons

Agreement with wave turbulence theory

Abstract

We report the observation of capillary wave turbulence on the surface of a fluid layer in a low-gravity environment. In such conditions, the fluid covers all the internal surface of the spherical container which is submitted to random forcing. The surface wave amplitude displays power-law spectrum over two decades in frequency, corresponding to wavelength from $mm$ to a few $cm$. This spectrum is found in roughly good agreement with wave turbulence theory. Such a large scale observation without gravity waves has never been reached during ground experiments. When the forcing is periodic, two-dimensional spherical patterns are observed on the fluid surface such as subharmonic stripes or hexagons with wavelength satisfying the capillary wave dispersion relation.