Influence of the multipole order of the source on the decay of an inertial wave beam in a rotating fluid

Abstract

We analyze theoretically and experimentally the far-field viscous decay of a two-dimensional inertial wave beam emitted by a harmonic line source in a rotating fluid. By identifying the relevant conserved quantities along the wave beam, we show how the beam structure and decay exponent are governed by the multipole order of the source. Two wavemakers are considered experimentally, a pulsating and an oscillating cylinder, aiming to produce a monopole and a dipole source, respectively. The relevant conserved quantity which discriminates between these two sources is the instantaneous flowrate along the wave beam, which is non-zero for the monopole and zero for the dipole. For each source the beam structure and decay exponent, measured using particle image velocimetry, are in good agreement with the predictions.

References in corpus (3)

• Laboratory experiments on the generation of internal tidal beams over steep slopes
• Inertial waves and modes excited by the libration of a rotating cube
• Earth rotation prevents exact solid body rotation of fluids in the laboratory

Cited by in corpus (9)

• Quantitative experimental observation of weak inertial-wave turbulence
• Shortcut to geostrophy in wave-driven rotating turbulence: the quartetic instability
• Linear and nonlinear regimes of an inertial wave attractor
• Internal wave turbulence in a stratified fluid with and without eigenmodes of the experimental domain
• Three-dimensionality of the triadic resonance instability of a plane inertial wave
• Flow past a sphere translating along the axis of a rotating fluid: Revisiting numerically Maxworthy's experiments
• Two-dimensionalization of the flow driven by a slowly rotating impeller in a rapidly rotating fluid
• Internal shear layers in librating spherical shells: the case of attractors
• Internal shear layers generated by a vertically oscillating cylinder in unbounded and bounded rotating fluids