All Outputs (8)

Lagrangian filtering for wave–mean flow decomposition (2025)
Journal Article
Baker, L. E., Kafiabad, H. A., Maitland-Davies, C., & Vanneste, J. (2025). Lagrangian filtering for wave–mean flow decomposition. Journal of Fluid Mechanics, 1009, Article A40. https://doi.org/10.1017/jfm.2025.42

Geophysical flows are typically composed of wave and mean motions with a wide range of overlapping temporal scales, making separation between the two types of motion in wave-resolving numerical simulations challenging. Lagrangian filtering – whereby... Read More about Lagrangian filtering for wave–mean flow decomposition.

Inhomogeneity-induced wavenumber diffusion (2025)
Journal Article
Cox, M. R., Kafiabad, H. A., & Vanneste, J. (2025). Inhomogeneity-induced wavenumber diffusion. Journal of Fluid Mechanics, 1007, Article A15. https://doi.org/10.1017/jfm.2025.23

Inertia-gravity waves are scattered by background flows as a result of Doppler shift by a non-uniform velocity. In the Wentzel-Kramers-Brillouin regime, the scattering process reduces to a diffusion in spectral space. Other inhomogeneities that the w... Read More about Inhomogeneity-induced wavenumber diffusion.

Computing Lagrangian means (2023)
Journal Article
Kafiabad, H. A., & Vanneste, J. (2023). Computing Lagrangian means. Journal of Fluid Mechanics, 960, Article A36. https://doi.org/10.1017/jfm.2023.228

Lagrangian averaging plays an important role in the analysis of wave–mean-flow interactions and other multiscale fluid phenomena. The numerical computation of Lagrangian means, e.g. from simulation data, is, however, challenging. Typical implementati... Read More about Computing Lagrangian means.

Inertia-gravity-wave diffusion by geostrophic turbulence: the impact of flow time dependence (2023)
Journal Article
Cox, M. R., Kafiabad, H. A., & Vanneste, J. (2023). Inertia-gravity-wave diffusion by geostrophic turbulence: the impact of flow time dependence. Journal of Fluid Mechanics, 958, Article A21. https://doi.org/10.1017/jfm.2023.83

The scattering of three-dimensional inertia-gravity waves by a turbulent geostrophic flow leads to the redistribution of their action through what is approximately a diffusion process in wavevector space. The corresponding diffusivity tensor was obta... Read More about Inertia-gravity-wave diffusion by geostrophic turbulence: the impact of flow time dependence.

Grid-based calculation of the Lagrangian mean (2022)
Journal Article
Kafiabad, H. A. (2022). Grid-based calculation of the Lagrangian mean. Journal of Fluid Mechanics, 940, Article A21. https://doi.org/10.1017/jfm.2022.233

Lagrangian averaging has been shown to be more effective than the Eulerian mean in separating waves from slow dynamics in two time scale flows. It also appears in many reduced models that capture the wave feedback on the slow flow. Its calculation, h... Read More about Grid-based calculation of the Lagrangian mean.

Interaction of Near-Inertial Waves with an Anticyclonic Vortex (2021)
Journal Article
Kafiabad, H., Vanneste, J., & Young, W. R. (2021). Interaction of Near-Inertial Waves with an Anticyclonic Vortex. Journal of Physical Oceanography, 51(6), 2035-2048. https://doi.org/10.1175/JPO-D-20-0257.1

Anticyclonic vortices focus and trap near-inertial waves so that near-inertial energy levels are elevated within the vortex core. Some aspects of this process, including the nonlinear modification of the vortex by the wave, are explained by the exist... Read More about Interaction of Near-Inertial Waves with an Anticyclonic Vortex.

Inertia-gravity-wave scattering by three-dimensional geostrophic turbulence (2021)
Journal Article
Savva, M. A. C., Kafiabad, H. A., & Vanneste, J. (2021). Inertia-gravity-wave scattering by three-dimensional geostrophic turbulence. Journal of Fluid Mechanics, 916, Article A6. https://doi.org/10.1017/jfm.2021.205

In rotating stratified flows including in the atmosphere and ocean, inertia-gravity waves (IGWs) often coexist with geostrophically balanced turbulent flows. Advection and refraction by such flows lead to wave scattering, redistributing IGW energy in... Read More about Inertia-gravity-wave scattering by three-dimensional geostrophic turbulence.

Wave-averaged balance: a simple example (2021)
Journal Article
Kafiabad, H. A., Vanneste, J., & Young, W. R. (2021). Wave-averaged balance: a simple example. Journal of Fluid Mechanics, 911, Article R1. https://doi.org/10.1017/jfm.2020.1032

In the presence of inertia-gravity waves, the geostrophic and hydrostatic balance that characterises the slow dynamics of rapidly rotating, strongly stratified flows holds in a time-averaged sense and applies to the Lagrangian-mean velocity and buoya... Read More about Wave-averaged balance: a simple example.