Merging the adaptive networks with the free space optical (FSO) communication technology is a very interesting field of research because by adding the benefits of this technology, the adaptive networks become more efficient, cheap and secure. This is due to the fact that FSO communication uses unregistered visible light bandwidth instead of the overused radio spectrum. However, in spite of all ...

Optical turbulence within earth’s atmosphere plays a significant role in electromagnetic radiation propagation from a high energy laser. The index of refraction structure constant, Cn2, characterizes turbulent spatial fluctuations due to temperature gradients. These changes in the index of refraction affect the intensity of the laser wave front on its intended target. It is important to charact...

This paper presents a comparison between measured and predicted results of the in-cylinder tumble flow and the flow coefficient generated by a port-valve-liner assembly on a steady-flow test bench. In this study, computational fluid dynamics (CFD) methods were employed to gain further insight into characteristics of an engine. The purpose was to advance understanding of the stationary turbulenc...

This report presents an evaluation of the steady-state capability of the turbulence models available in the commercial CFD code FLUENT 6.0, for their application to the simulation of hydrofoil turbulent boundary layer separation at high-Reynolds numbers. Four widely applied two-equation RANS turbulence models were qualitatively and quantitatively assessed through comparison with high-quality ex...

We provide a brief overview of recent advances and outstanding issues in simulations of interstellar turbulence, including isothermal models for interior structure of molecular clouds and larger-scale multiphase models designed to simulate the formation of molecular clouds. We show how self-organization in highly compressible magnetized turbulence in the multiphase ISM can be exploited in simpl...

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...

........................................................................................................... 6 ABBREVIATIONS.................................................................................................. 7 ORIGINAL PAPERS .............................................................................................. 9 INTRODUCTION ..................................................

Recent progress and remaining challenges related to the understanding and prediction of turbulent flow are described. This is done by explaining the need for the development and basic features of unified turbulence models which integrate, recover and extend well known existing computational methods for turbulent flow calculations. The availability of unified turbulence models enables a signific...

A new subgrid eddy-viscosity model is proposed in this paper. Full details of the derivation of the model are given with the assumption of homogeneous turbulence. The formulation of the model is based on the dynamic equation of the structure function of resolved scale turbulence. By means of the local volume average, the effect of the anisotropy is taken into account in the generalized Kolmogor...