In the present work the generation of zonal flows in collisionless trapped electron mode (TEM) turbulence is studied analytically. A reduced model for TEM turbulence is utilized based on an advanced fluid model for reactive drift waves. An analytical expression for the zonal flow growth rate is derived and compared with the linear TEM growth, and its scaling with plasma parameters is examined f...

The propagation of microwaves across a turbulent plasma density layer is investigated with fullwave simulations. To properly represent a fusion edge-plasma, drift-wave turbulence is considered based on the Hasegawa-Wakatani model. Scattering and broadening of a microwave beam whose amplitude distribution is of Gaussian shape is studied in detail as a function of certain turbulence properties. P...

Occurrences of clear air turbulence in the stratosphere at altitudes of 45,000 to 68,000 f t are analyzed in terms of observed variability in vertical temperature gradients and balloon ascensional rates based on nearby radiosonde data. While the magnitudes of both parameters are positively correlated with the probability of encountering turbulence, the temperature gradient variability has a hig...

The structure constant of the atmospheric refractive index is used for characterizing the turbulence strength and for predicting the scintillation of electromagnetic waves in atmosphere. It is measured continuously in Prague using an optical scintillometer. First monthly and seasonal statistics obtained from the data gathered in the summer 2011 are provided. Lognormal distribution parameters ar...

A full scale physical model of a thin slab caster with a four-hole design submerged entry nozzle (SEN) was constructed. On the basis of the dimensionless Reynolds and Froude similitude criteria, the fluid flow in a full-scale model is similar to that of the actual system and, hence, the data obtained from the water model can be applied to the actual system. In order to determine the optimum ope...

General hierarchical lattices of coupled maps are considered as dynamical systems. These models may describe many processes occurring in heterogeneous media with tree-like structures. The transition to turbulence via spatiotemporal intermittency is investigated for these geometries. Critical exponents associated to the onset of turbulence are calculated as functions of the parameters of the sys...

Many processes interact in a complex and highly non-linear way during the life cycle of fog, the turbulent transport being among them. Observations and analysis of turbulence are, then, fundamental to our understanding of the physical mechanisms involved with fog formation, evolution and dissipation. Data gathered by fast-response sonic anemometers are processed using wavelet methods in order t...

We study the change in the degree of coherence of a partially coherent flat-topped (PCFT) beam propagating through atmospheric turbulence. It is shown analytically that with a fixed set of source parameters and under a particular atmospheric turbulence model, a PCFT beam propagating through atmospheric turbulence reaches its maximum value of coherence after propagating a particular distance, an...

Turbulence in the Earth’s atmosphere is a major obstacle to the detection of planets with coronographic and interferometric methods from the ground. It limits the contrast achievable with high-resolution imaging and the precision of astrometric measurements. Atmospheric turbulence also determines many of the key design parameters of adaptive optics systems and interferometers: site selection, o...

We present experimental results on the properties of bounded turbulence in thin fluid layers. In contrast with the theory of two-dimensional 2D turbulence, the effects of the bottom friction and of the spectral condensation of the turbulence energy are important in our experiment. Here we investigate how these two factors affect statistical moments of turbulent fluctuations. The inverse energy ...