We present a simple exact formula for the three point velocity correlation functions in two dimensional turbulence which is valid on all scales and which interpolates between the direct and inverse cascade regimes. As expected, these correlation functions are universal in these extreme regimes. We also discuss the effect of anisotropy and friction. Member of the CNRS; [email protected]...

Astrophysical turbulence is magnetohydrodynamic (MHD) in its nature. We discuss fundamental properties of MHD turbulence. In particular, we discuss the generation of compressible MHD waves by Alfvenic turbulence and show that this process is inefficient. This allows us to study the evolution of different types of MHD perturbations separately. We describe how to separate MHD fluctuations into 3 ...

Small-scale anisotropic intermittency is examined in three-dimensional incompressible magnetohydrodynamic turbulence subjected to a uniformly imposed magnetic field. Orthonormal wavelet analyses are applied to direct numerical simulation data at moderate Reynolds number and for different interaction parameters. The magnetic Reynolds number is sufficiently low such that the quasistatic approxima...

When magnetic energy density is much larger than that of matter, as in pulsar/black hole magnetospheres, the medium becomes force-free and we need relativity to describe it. As in non-relativistic magnetohydrodynamics (MHD), Alfvénic MHD turbulence in the relativistic limit can be described by interactions of counter-traveling wave packets. In this paper we numerically study strong imbalanced M...

The Very Local Interstellar Medium (VLISM) contains clouds which consist of partially-ionized plasma. These clouds can be effectively diagnosed via high resolution optical and ultraviolet spectroscopy of the absorption lines they form in the spectra of nearby stars. Information provided by these spectroscopic measurements includes values for ξ , the root-mean-square velocity fluctuation due to ...

Results of a study of dispersive Alfvén modes propagating outward from the Sun in streaming inhomogeneous plasma are presented for the inner heliosphere (1 AU) region. The results clearly show that a combination of nonlinear wave–particle and wave–wave interactions of outward-only Alfvén modes initially propagating along the local background magnetic field is perfectly capable of explaining th...

Abstract The scaling of magnetic fluctuations provides crucial information for the understanding solar wind turbulence. However, observed contain not only turbulence but also structures, leading to violation time stationarity. This would conceal true and influence determination sampling angle with respect local background field. Here, investigate anisotropy, we utilize a simple effective criter...

Models of planetary, atmospheric and oceanic circulation involve eddy viscosity and eddy diffusivity, KM and KH , that account for unresolved turbulent mixing and diffusion. The most sophisticated turbulent closure models used today for geophysical applications belong in the family of the Reynolds stress models. These models are formulated for the physical space variables; they consider a hiera...

Abstract The restoration of symmetries is one the most fascinating properties turbulence. We report a study emergence isotropy in Gross-Pitaevskii model with anisotropic forcing. Inspired by recent experiments, we dynamics Bose-Einstein condensate cylindrical box driven along symmetry axis trap spatially uniform force. introduce measure anisotropy A ( k , t ) defined on momentum distributions <...