The coherent/incoherent decomposition of the subgrid-scale stresses based on the wavelet de-noising procedure is exploited in the framework of large-eddy simulation of turbulence. Dynamic a-priori tests based on the perfect modeling approach are performed for decaying isotropic turbulence. The theoretical performances of deterministic/stochastic subgrid-scale models are evaluated during the sim...

The analytical formulas for the average intensity and power in the bucket of the relay propagation of partially coherent cosh-Gaussian (ChG) beams in non-Kolmogorov turbulence have been derived based on the extended Huygens-Fresnel principle. The influences of the beam parameters, relay system parameters and the non-Kolmogorov turbulence parameters on relay propagation are investigated by numer...

The propagation of an ON–OFF keying modulated optical signal through an optical atmospheric turbulent channel is considered. The intensity fluctuations of the signal observed at the receiver are modeled using a gamma–gamma distribution. The capacity of this channel is determined for a wide range of turbulence conditions. For a zero inner scale, the capacity decreases monotonically as the turbul...

The specific objectives of this project are to obtain a critical evaluation of turbulence closure models that are commonly used in the coastal ocean, and to identify ways to improve these models. Of particular interest are the MY-2.5 model (Mellor and Yamada, 1974, 1982) and the k-e model (e.g., Rodi, 1987), which involve coupled equations describing turbulent kinetic energy and turbulent scale...

Turbulent-flame speeds in methane–air mixtures were measured in a Taylor–Couette apparatus with counter-rotating cylinders, used to generate turbulence that is nearly homogeneous and isotropic over many integral length and time scales. While laminar-flame propagation is found to be influenced by the Darrieus– Landau instability and heat loss to the walls of the apparatus, turbulent-flame propag...

A review of recent experimental studies of turbulence suppression by mean flows in quasi-two-dimensional fluids is presented. Large-scale mean flows develop during spectral condensation of 2D turbulence as a result of the inverse energy cascade in spatially bounded flow. The spectral energy which is accumulated at the largest scale supports the mean flow which in turn affects turbulence. We sho...

Turbulent magnetic fields abound in nature, pervading astrophysical, solar, terrestrial and laboratory plasmas. Understanding the ubiquity of magnetic turbulence and its role in the universe is an outstanding scientific challenge. Here, we report on the transition of magnetic turbulence from an initially electron-driven regime to one dominated by ion-magnetization in a laboratory plasma produce...

The problems with explaining the Small Ionized and Neutral Structures (SINS) appealing to turbulence stem from inefficiency of the Kol-mogorov cascade in creating large fluctuations at sufficiently small scales. However , other types of cascades are possible. When magnetic turbulence in a fluid with viscosity that is much larger than resistivity gets to a viscous damping scale, the turbulence d...

The origin of the empirical laws of galactic-scale star formation are considered in view of the self-similar nature of interstellar gas and the observation that most local clusters are triggered by specific high-pressure events. The empirical laws suggest that galactic-scale gravity is involved in the first stages of star formation, but they do not identify the actual triggering mechanisms for ...

Collective motion of self-sustained swarming flows has recently provided examples of small-scale turbulence arising where viscous effects are dominant. We report the first observation of universal enstrophy cascade in concentrated swarming sperm consistent with a body of evidence built from various independent measurements. We found a well-defined k^{-3} power-law decay of a velocity field powe...