Systematic analysis of numerical simulations of two-dimensional magnetohydrodynamic turbulence reveals the presence of a large number of X-type neutral points where magnetic reconnection occurs. We examine the statistical properties of this ensemble of reconnection events that are spontaneously generated by turbulence. The associated reconnection rates are distributed over a wide range of value...

Fluid turbulence is commonly modeled by the Navier-Stokes equations with a large Reynolds number. However, direct numerical simulations are not possible in practice, so that turbulence modeling is introduced. We study artificial spectral viscosity models that render the simulation of turbulence tractable. We show that the models are well posed and have solutions that converge, in certain parame...

The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by gradients in the electron temperature. It is found that electron temperature gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essenti...

We report the observation of the crossover between gravity and capillary wave turbulence on the surface of mercury. The probability density functions of the turbulent wave height are found to be asymmetric and thus non-Gaussian. The surface wave height displays power-law spectra in both regimes. In the capillary region, the exponent is in fair agreement with weak turbulence theory. In the gravi...

Stochastic sound sources derived from Reynolds Averaged Navier-Stokes (RANS) solution are recognized in Computational Aeroacoustics as one possible way to efficiently predict broadband sound. In this paper a stochastically forced linear advection-diffusiondissipation equation is introduced. The model provides spectra and anisotropic two-point correlations that otherwise have to be incorporated ...

Random networks of coupled phase oscillators with phase shifts in the interaction functions are considered. In such systems, extensive chaos (turbulence) is observed in a wide range of parameters. We show that, by introducing global feedback, the turbulence can be suppressed and a transition to synchronous oscillations can be induced. Our attention is focused on the transition scenario and the ...

In the paper, a method to calculate the time evolution turbulence wavefronts based on the covariance method is theoretically presented in detail. According to it, the time-evolution wavefronts disturbed by atmospheric turbulence were experimentally generated by our LC atmospheric turbulence simulator (ATS) based on liquid crystal on silicon (LCOS) with high pixel density, and measured with a wa...

Consider the dynamics of turbulent flow in rivers, estuaries and floods. Based on the widely used k-ǫ model for turbulence, we use the techniques of centre manifold theory to derive dynamical models for the evolution of the water depth and of vertically averaged flow velocity and turbulent parameters. This new model for the shallow water dynamics of turbulent flow: resolves the vertical structu...

A self-consistent renormalization scheme has been applied to nonhelical magnetohydrodynamic (MHD) turbulence with zero cross helicity. Kolmogorov's 5/3 power law has been shown to be a consistent solution for d> or =d(c) approximately 2.2. For Kolmogorov's solution, both renormalized viscosity and resistivity are positive for the whole range of parameters. Various cascade rates and Kolmogorov's...

The basic scales of motion and computational requirements for low frequency fluid drift turbulence are summarised in tutorial fashion. Basic signatures for each of the competing eigenmode types are given, some of which are accessible experimentally. The emphasis is on edge turbulence since it is less intuitive. The difference in physical mechanism between linear instabilities and fully develope...