Supersonic turbulence plays an important role in a number of extreme astrophysical and terrestrial environments, yet its understanding remains rudimentary. We use data from a three-dimensional simulation of supersonic isothermal turbulence to reconstruct an exact fourth-order relation derived analytically from the Navier–Stokes equations (Galtier and Banerjee, Phys. Rev. Lett., vol. 107, 2011, ...

In developed turbulence, the effective magnetic pressure of a large-scale field (non-turbulent plus turbulent contributions) can become negative. This is known to lead to a large-scale instability in strongly stratified turbulence that produces spontaneous magnetic flux concentrations. Previous studies using a horizontal magnetic field resulted in elongated field concentrations with a strength ...

With the aim of understanding the anomalous transport mechanism in the magnetic confinement fusion plasma and quantitatively predicting the transport level, gyrokinetic simulations of plasma turbulence have been carried out by means of the originally developed code (GKV code). The GKV simulations solving time-evolutions of particle distribution function in the five-dimensional phase-space have ...

The equations governing meridional circulation in uniformly rotating stars are discussed, allowing for turbulence and for baroclinic effects. Relations for barotropic stars with steady motions are generalized to baroclinic stars with turbulence. The circulation luminosity (i.e., the luminosity carried by circulation through a level surface) is shown to be zero in barotropic layers and positive ...

The relation between magnetic geometry and the level of ion-temperature-gradient (ITG) driven turbulence in stellarators is explored through gyrokinetic theory and direct linear and nonlinear simulations. It is found that the ITG radial heat flux is sensitive to details of the magnetic configuration that can be understood in terms of the linear behavior of zonal flows. The results throw light o...

The interaction of long-wavelength anisotropic drift waves with the plasma turbulence of electron density advection is shown to produce the inverse energy transfer that condenses onto zonal modes, despite the expectation of forward transfer on the basis of nonconservation of enstrophy. Wave triads with an unstable wave and two waves of a separate, damped spectrum carry the transfer, provided th...

Turbulent flows are often observed to be organized into large-spatial-scale jets such as the familiar zonal jets in the upper levels of the Jovian atmosphere. These relatively steady large-scale jets are not forced coherently but are maintained by the much smaller spatialand temporal-scale turbulence with which they coexist. The turbulence maintaining the jets may arise from exogenous sources s...

Modelling of wind farms using computational fluid dynamics (CFD) resolving the flow field around each wind turbine’s blades on a moving computational grid is still too costly and time consuming in terms of computational capacity and effort. One strategy is to use sub-models for the wind turbines, and sub-grid models for turbulence production and dissipation to model the turbulent viscosity accu...

The dynamics of soot formation in turbulent ethylene–air nonpremixed counterflow flames is studied using direct numerical simulation (DNS) with a semi-empirical soot model and the discrete ordinate method (DOM) as a radiation solver. Transient characteristics of soot behavior are studies by a model problem of flame interaction with turbulence inflow at various intensities. The interaction betwe...