Internal gravity waves in stratified flows with and without vortical modes
arXiv:2303.01570 · doi:10.1103/PhysRevFluids.9.024604
Abstract
The comprehension of stratified flows is important for geophysical and astrophysical applications. The Weak Wave Turbulence theory aims to provide a statistical description of internal gravity waves propagating in the bulk of such flows. However, internal gravity waves are usually perturbed by other structures present in stratified flow, namely the shear modes and the vortical modes. In order to check whether a weak internal gravity wave turbulence regime can occur, we perform direct numerical simulations of stratified turbulence without shear modes, and with or without vortical modes at various Froude and buoyancy Reynolds numbers. We observe that removing vortical modes naturally helps to have a better overall balance between poloidal kinetic energy, involved in internal gravity waves, and potential energy. However, conversion between kinetic energy and potential energy does not necessarily show fluctuations around zero in our simulations, as we would expect for a system of weak waves. A spatiotemporal analysis reveals that removing vortical modes helps to concentrate the energy around the wave frequency, but it is not enough to observe a weak wave turbulence regime. Yet, we observe that internal gravity waves whose frequency are large compared to the eddy turnover time are present, and we also find evidences for slow internal gravity waves interacting by Triadic Resonance Instabilities in our strongly stratified flows simulations. Finally, we propose conditions that should be fulfilled in order to observe a weak internal gravity waves turbulence regime in real flows.
arXiv comment27 pages, 17 figures
References in corpus (28)
- A weak turbulence theory for incompressible MHD
- Critical balance in magnetohydrodynamic, rotating and stratified turbulence: towards a universal scaling conjecture
- Hamiltonian formalism and the Garrett-Munk spectrum of internal waves in the ocean
- Experiments in Surface Gravity-Capillary Wave Turbulence
- Forced Stratified Turbulence: Successive Transitions with Reynolds Number
- Direct Evidence of the Transition from Weak to Strong MHD Turbulence
- Intertial wave turbulence driven by elliptical instability
- Turbulence of Weak Gravitational Waves in the Early Universe
- Quantitative experimental observation of weak inertial-wave turbulence
- Discrete and mesoscopic regimes of finite-size wave turbulence
- Waves and vortices in the inverse cascade regime of stratified turbulence with or without rotation
- Shortcut to geostrophy in wave-driven rotating turbulence: the quartetic instability
- Experimental study of the non-linear saturation of the elliptical instability: inertial wave turbulence versus geostrophic turbulence
- Non stationary wave turbulence in an elastic plate
- Succession of resonances to achieve internal wave turbulence
- Energy spectrum of two-dimensional acoustic turbulence
- Downscale energy fluxes in scale invariant oceanic internal wave turbulence
- Parametric instability and wave turbulence driven by tidal excitation of internal waves
- Testing wave turbulence theory for Gross-Pitaevskii system
- Identification of Separation Wavenumber between Weak and Strong Turbulence Spectra for Vibrating Plate
- Energy-flux vector in anisotropic turbulence: application to rotating turbulence
- Internal wave turbulence in a stratified fluid with and without eigenmodes of the experimental domain
- Nonlinear wave-wave interactions in stratified flows: Direct numerical simulations
- FluidDyn: a Python open-source framework for research and teaching in fluid dynamics
- FluidFFT: common API (C++ and Python) for Fast Fourier Transform HPC libraries
- FluidSim: modular, object-oriented Python package for high-performance CFD simulations
- Turbulent regimes in collisions of 3D Alfvén-wave packets
- Energy-based analysis and anisotropic spectral distribution of internal gravity waves in strongly stratified turbulence