Multiscales and cascade in isotropic turbulence

The central problem of fully developed turbulence is the energy cascading process. It has revisited all attempts at a full physical understanding or mathematical formulation. The main reason for this failure are related to the large hierarchy of scales involved, the highly nonlinear character inherent in the Navier-Stokes equations, and the spatial intermittency of the dynamically active regions. Richardson has described the interplay between large and small scales and the phenomena so described are known as the Richardson cascade. This local interplay also forms the basis of a theory by Kolmogorov. In this letter, we use the explicit map method to analyze the nonlinear dynamical behavior for cascade in isotropic turbulence. This deductive scale analysis is shown to provide the first visual evidence of the celebrated Richardson cascade, and reveals in particular its multiscale character. The results also indicate that the energy cascading process has remarkable similarities with the deterministic construction rules of the logistic map. Cascade of period-doubling bifurcations have been seen in this isotropic turbulent systems that exhibit chaotic behavior. The `cascade' appears as an infinite sequence of period-doubling bifurcations.Comment: 7 pages,1 figur

Large scale dynamics in two-dimensional turbulence

We consider freely decaying two-dimensional isotropic turbulence. It is usually assumed that, in such turbulence, the energy spectrum at small wave number, takes the form, where is the two-dimensional version of Loitsyansky's integral. In this paper, we developed a simple model for large scale dynamics of free decay two-dimensional turbulence based on the statistical solution of Navier-Stokes equation. We provide one possible explanation for the large scale dynamics in two-dimensional turbulence.Comment: 5 pages, 0 figures, 1 tabl

Integrability and Hamiltonian system in isotropic turbulence

We present developments of the Hamiltonian approach to problems of the freely decay of isotropic turbulence, and also consider specific applications of the modified Prelle-Singer procedure to isotropic turbulence. It demonstrates that a nonlinear second order ordinary differential equation is intimately related to the self-preserving solution of Karman-Howarth equation, admitting time-dependent first integrals and also proving the nonstandard Hamiltonian structure, as well as the Liouville sense of integrability.Comment: 7 pages;0 figure

Nonlinear dynamical systems and linearly forced isotropic turbulence

In this paper, we present an extensive study of linearly forced isotropic turbulence. By using an analytical method, we identified two parametric choices that are new to our knowledge. We proved that the underlying nonlinear dynamical system for linearly forced isotropic turbulence is the general case of a cubic Lienard equation with linear damping (Dumortier and Rousseau 1990).Comment: 6 pages, 0 figure

A new class of exact solution of two-dimensional incompressible vortex motion

At present in the fluid mechanics, mostly one like to use the vortex as a basic physical quantity, such that some exact solutions is based on the vorticity evolution equation. For the vortex flow problem with axisymmetry, it is well known that there exists in the circulation as a mechanical system of basic physical quantities. In this paper, from the basic dynamic equation of the mechanical system, the self-similar solution, eigenvalue system into a self- consistent, new exact solutions of the two-dimensional circular symmetric vortex flow are obtained, and some further comparison are made with the known exact solutions. Key words: vortex motion, exact solution, eigenvalue systemComment: 6 pages, 0 figur

Logistic map and micro-structure of isotropic turbulent flow

ONE of the main goals in the development of theory of chaotic dynamical system has been to make progress in understanding of turbulence. The attempts to related turbulence to chaotic motion got strong impetus from the celebrated paper by Ruelle and Takens . Considerable success has been achieved mainly in the area: the onset of turbulence. For fully developed turbulence, many questions remain unanswered. The aim of this letter is to show that there are dynamical systems that are much simpler than the Navier-Stokes equations but that can still have turbulent states and for which many concepts developed in the theory of dynamical systems can be successfully applied. In this connection we advocate a broader use of the universal properties of a wide range of isotropic turbulence phenomena. Even for the case of fully developed turbulence, which contains an extreme range of relevant length scales, it is possible, by using the present model, to reproduce a surprising variety of relevant features, such as multifractal cascade, intermittency. This letter reverts to possible applications of the Navier-Stokes equations to studies of the nature of turbulence.Comment: 8 pages, 7 figures, 1 tabl

Entropy and weak solutions in the LBGK model

In this paper, we derive entropy functions whose local equilibria are suitable to recover the Euler-like equations in the framework of the Lattice Boltzmann method. Numerical examples are also given, which are consistent with the above theoretical arguments.Comment: 13pages,2 figure

Nonlinear dynamical systems and bistability in linearly forced isotropic turbulence

In this letter, we present an extensive study of the linearly forced isotropic turbulence. By using analytical method, we identify two parametric choices, of which they seem to be new as far as our knowledge goes. We prove that the underlying nonlinear dynamical system for linearly forced isotropic turbulence is the general case of a cubic Lienard equation with linear damping. We also discuss a Fokker-Planck approach to this new dynamical system,which is bistable and exhibits two asymmetric and asymptotically stable stationary probability densities.Comment: 7 pages, 1 figur

Review and Update of the Compactified M/string Theory Prediction of the Higgs Boson Mass and Properties

The August 2011 Higgs mass prediction was based on an ongoing six year project studying M-theory compactified on a manifold of G2 holonomy, with significant contributions from Jing Shao, Eric Kuflik, and others, and particularly co-led by Bobby Acharya and Piyush Kumar. The M-theory results include: stabilization of all moduli in a de Sitter vacuum; gauge coupling unification; derivation of TeV scale physics (solving the hierarchy problem); the derivation that generically scalar masses are equal to the gravitino mass which is larger than about 30 TeV; derivation of the Higgs mechanism via radiative electroweak symmetry breaking; absence of the flavor and CP problems, and the accommodation of string axions. tan beta and the mu parameter are part of the theory and are approximately calculated; as a result, the little hierarchy problem is greatly reduced. This paper summarizes the results relevant to the Higgs mass prediction. A recent review describes the program more broadly. Some of the results such as the scalar masses being equal to the gravitino mass and larger than about 30 TeV, derived early in the program, hold generically for compactified string theories as well as for compactified M-theory, while some other results may or may not. If the world is described by M-theory compactified on a G2 manifold and has a Higgs mechanism (so it could be our world) then the Higgs mass was predicted to be 126 +/- 2 GeV before the measurement. The derivation has some assumptions not related to the Higgs mass, but involves no free parameters.Comment: 10 pages, 4 figures, Invited review for the International Journal of Modern Physics

Probability Distribution of a Passive Scalar in Isotropic Turbulence

In this letter, we present developments of the Hamiltonian approach to problems of the probability distribution for a passive scalar in isotropic turbulence, and also considers specific applications of the modified Prelle-Singer procedure to turbulence models. The following key questions are discussed and solved: what is the general dynamical structure of the resulting scale equation permitted by passive scalar turbulence models? What are the general requirements of the relations between canonical variables and the canonical variabes representation for turbulence by using canonical variables? It is shown that the existence of the Haniltonian representation in turbulence is a privilege of only turbulence systems for which the variational principle of least action is impossible The master equation of the probability distribution of a passive scalar in isotropic turbulence can also be deduced explicitly.Comment: 7pages,0figure