Incompressible energy spectrum from wave turbulence

Wave-number spectrum of drift-wave turbulence.

A simple model for the evolution of turbulence fluctuation spectra, which includes neighboring interactions leading to the usual dual cascade as well as disparate scale interactions corresponding to refraction by large scale structures, is derived. The model recovers the usual Kraichnan-Kolmogorov picture in the case of exclusively local interactions and midrange drive. On the other hand, when ...

Energy spectrum of quasigeostrophic turbulence.

We consider the energy spectrum of a quasigeostrophic model of forced, rotating turbulent flow. We provide a rigorous a priori bound E(k)<or=Ck(-2) valid for wave numbers that are smaller than a wave number associated with the forcing injection scale. This upper bound separates this spectrum from the Kolmogorov-Kraichnan k(-5/3) energy spectrum that is expected in a two-dimensional Navier-Stoke...

Energy cascades in physical scales of 3D incompressible magnetohydrodynamic turbulence

Fluctuations of energy flux in wave turbulence.

We report that the power driving gravity and capillary wave turbulence in a statistically stationary regime displays fluctuations much stronger than its mean value. We show that its probability density function (PDF) has a most probable value close to zero and involves two asymmetric roughly exponential tails. We understand the qualitative features of the PDF using a simple Langevin-type model.

Energy spectrum of buoyancy-driven turbulence.

Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux Π(u), we demonstrate that, for stably stratified flows, the kinetic energy spectrum E(u)(k)∼k(-11/5), the potential energy spectrum E(θ)(k)∼k(-7/5), and Π(u)(k)∼k(-4/5) are consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential ener...