the purpose of this paper is to studying nonlinear k-ε turbulence models and its advantages in internal combustion engines, since the standard k-ε model is incapable of representing the anisotropy of turbulence intensities and fails to express the reynolds stresses adequately in rotating flows. therefore, this model is not only incapable of expressing the anisotropy of turbulence in an engine c...

In this paper, the effects of turbulent biological tissues (TBT) on propagation properties coherent Laguerre-Gaussian (CLG) beams are studied. Based turbulence theory and using power spectrum refractive-index model, expression formulae average irradiance intensity spreading a CLG beam propagating in TBT derived. The influence distance, orders, wavelengths tissue parameters then investigated num...

In this contribution we present a first application of the ongoing numerical simulations that are carried out in order to study the adaptive optics (AO) correction and the subsequent imaging post-processing when observing with the Large Binocular Telescope (LBT) interferometer. The simulation tool used as a starting point for this study is the software package CAOS 2.0 (Code for Adaptive Optics...

Three-dimensional finite-volume-based numerical models of fluid, heat, and mass transport have been developed and applied to help explain the complex inter-related phenomena of multiphase fluid flow, superheat dissipation, and grade intermixing during the continuous casting of steel slabs. Gas bubbles are simulated using a continuum model, which calculates the volume fraction and velocities of ...

We first present a new formulation of parabolic approximation of the Maxwell equations for heterogeneous dielectric materials. We then discuss rigorous results about selfaveraging scaling limits of parabolic waves in terms of the Wigner distribution function. Among the 6 possible scaling limits two are exactly solvable. We use the Green function to analyze the time reversal operation in turbule...

After a brief summary of experimental results focussed on plane Couette flow and contrasting the low-Reynolds numbers transition between laminar flow and the turbulent spot regime, with its high-Reynolds counterpart between homogeneous turbulence and turbulent stripes, we introduce a hierarchy of models from conceptual models designed to answer the most basic questions to semi-realistic models ...

The Rayleigh-Taylor (RT) instability affects a vast range of High Energy Density (HED) length scales, spanning from supernova explosions (10$^{13}$ m) to inertial confinement fusion (10$^{-6}$ m). In fusion, the RT is known induce mixing or turbulent transition, which in turn cools hot spot and hinders ignition. fine-scale features instability, are difficult image HED physics, may help determin...

A beam emission spectroscopy (BES) system has been installed on the National Spherical Torus Experiment (NSTX) to study ion gyroscale fluctuations. The BES system measures D(α) emission from a deuterium neutral heating beam. The system includes two optical views centered at r/a≈0.45 and 0.85 and aligned to magnetic field pitch angles at the neutral beam. f/1.5 collection optics produce 2-3 cm s...

Two front instabilities in a reaction-diffusion system are shown to lead to the formation of complex patterns. The first is an instability to transverse modulations that drives the formation of labyrinthine patterns. The second is a nonequilibrium Ising-Bloch (NIB) bifurcation that renders a stationary planar front unstable and gives rise to a pair of counterpropagating fronts. Near the NIB bif...

in this research, the effect of micro turbulence on the flotation rate of quartz particles was investigated. the maximum particle reynolds number (rep) was obtained at 60.25 with a particle size of -500+420 µm, impeller speed of 900 rpm, bubble surface area flux of 10.21 1/s and micro scale turbulence size of 162 µm. when the micro turbulence size was equal to the particle size, the maximum flo...