Logarithmic Correlation Functions in Two Dimensional Turbulence

We consider the correlation functions of two-dimensional turbulence in the presence and absence of a three-dimensional perturbation, by means of conformal field theory. In the persence of three dimensional perturbation, we show that in the strong coupling limit of a small scale random force, there is some logarithmic factor in the correlation functions of velocity stream functions. We show that the logarithmic conformal field theory $c_{8,1}$ describes the 2D- turbulence both in the absence and the presence of the perturbation. We obtain the following energy spectrum $E(k) \sim k^{-5.125 } \ln(k )$ for perturbed 2D - turbulence and $E(k) \sim k^{-5 } \ln(k )$ for unperturbed turbulence. Recent numerical simulation and experimental results confirm our prediction.Comment: 14 pages ,latex , no figure

3-D Perturbations in Conformal Turbulence

The effects of three-dimensional perturbations in two-dimensional turbulence are investigated, through a conformal field theory approach. We compute scaling exponents for the energy spectra of enstrophy and energy cascades, in a strong coupling limit, and compare them to the values found in recent experiments. The extension of unperturbed conformal turbulence to the present situation is performed by means of a simple physical picture in which the existence of small scale random forces is closely related to deviations of the exact two-dimensional fluid motion.Comment: Discussion of intermittency improved. Figure include

Open-ocean convection: observations, theory and models

We review what is known about the convective process in the open ocean, in which the properties of large volumes of water are changed by intermittent, deep-reaching convection, triggered by winter storms. Observational, laboratory, and modeling studies reveal a fascinating and complex interplay of convective and geostrophic scales, the large-scale circulation of the ocean, and the prevailing meteorology. Two aspects make ocean convection interesting from a theoretical point of view. First, the timescales of the convective process in the ocean are sufficiently long that it may be modified by the Earth's rotation; second, the convective process is localized in space so that vertical buoyancy transfer by upright convection can give way to slantwise transfer by baroclinic instability. Moreover, the convective and geostrophic scales are not very disparate from one another. Detailed observations of the process in the Labrador, Greenland, and Mediterranean Seas are described, which were made possible by new observing technology. When interpreted in terms of underlying dynamics and theory and the context provided by laboratory and numerical experiments of rotating convection, great progress in our description and understanding of the processes at work is being made

Evaluation of Noise pollution in Omidiyeh city, 2015

Introduction and Purpose: Noise pollution is one of the important environmental problems that has been on a growing trend in the recent years. This study was conducted to evaluate the level of noise pollution in Omidiyeh city, Iran. Methods: Testo 815 sound level meter was employed to quantify the sound pressure level (SPL). The measurements were conducted during 7-9 am, 12- 14 am, and 19-21 pm, at three locations (one station in each of commercial, residential, and commercial-residential areas), and the results were compared with the standard level of noise pollution. Results: The results indicated that the SPL at all the specified times and areas were higher than the standard level. The mean SPL in commercial, residential, and commercial-residential areas were 72.86, 67.36, and 61.71 dB, respectively, which were 7.86, 7.36, and 6.71 dB higher than the standards of noise in the open air. Conclusion: This study showed that the SPL was higher than standard level, Therefor new approaches should be implemented to reduce the level of noise pollutio