http://www.chialvo.net/Curso/UBACurso/DIA9/Papers/Stamreview2012.pdf

The organization of physiological brain networks.

Turbulent flows with nonpremixed reactants

This paper uses numerical simulation to analyse the effects of uniform rotation on homogeneous turbulence. Both large-eddy and full simulations were made. The results indicate that the predominant effect of rotation is to decrease the rate of dissipation of the turbulence and increase the lengthscales, especially those along the axis of rotation. These effects are a consequence of the reduction, due to the generation of inertial waves, of the net energy transfer from large eddies to small ones. Experiments are also influenced by a more complicated interaction between the rotation and the wakes of the turbulence-generating grid which modifies the nominal initial conditions in the experiment. The latter effect is accounted for in simulations by modifying the initial conditions. Finally, a two-equation model is proposed that accounts for the effects of rotation and is able to reproduce the experimental decay of the turbulent kinetic energy.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022112085001550

Effect of rotation on isotropic turbulence - Computation and modelling

Dissipation in many-body systems: A geometric approach based on information theory

When focusing an Nd glass laser (frequency ωo) onto a cryogenic target (D2 or H2) quite intense lines with frequencies 2ωo, 3ω0/2, ω0/2 are found in the reflected light in both backward and 45° directions. The lines at 2ω0 and 3ω0/2 are broadened on the low frequency side only. The occurrence and broadening of such lines may be related to parametric excitation of waves.

Harmonic generation and parametric excitation of waves in a laser-created plasma

The foundations of nonequilibrium statistical mechanics, II

: A general theory of aerodynamic sound is developed. The basic equations of fluid mechanics are expressed in terms of velocity, enthalpy and entropy, and the velocity field is separated into irrotational and rotational parts with the latter being incompressible. A fundamental new concept, Bernoulli enthalpy, H, is introduced, again by analogy with homentropic-irrotational flow. It is shown that the source of the radiative sound field is the substantive rate of change of the Bernoulli enthalpy. Two basic conceptual issues of the modern theory of sound are resolved. First, the radiative sound is clearly separated from the source of sound with each part characterized by its own scalar field. Second, the Bernoulli source of sound is compact; i.e., it is confined to the region of rotational nonhomentropic flow.

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA040287&Location=U2&doc=GetTRDoc.pdf

Bernoulli enthalpy - A fundamental concept in the theory of sound

: A summary of both the theoretical and experimental studies carried out during the first year of a program of fundamental research on turbulent modeling is given. On the theoretical side, the application of a modeled tensor scale equation together with a modeled Reynolds stress equation to the case of homogeneous shear flow is discussed in some detail. It is shown that such modeling gives results that are in good agreement with experiment. On the experimental side, preliminary data on the effect of swirl on the structure of turbulence in an annular pipe flow are presented. (Author)

Fundamental Research in Turbulent Modeling.

: We develop a model of turbulent flows deduced from simple assumptions on the two-point tensor Rij whose first approximation consists in coupled equations for the Reynolds and scale tensors. The model, when specialized to homogeneous turbulence, contains two adjustable parameters with which we match the main features of both grid and sheared turbulence. The calculated integral scales for sheared turbulence are strongly directional. Thus the model allows one to compute, for the first time, a first approximation to the eddy structure in a sheared turbulent flow. (Author)

Fundamental Research in Turbulent Modeling, Part 1. Theory. Part 2. Experiment.

We develop a general technique for uniformizing asymptotic expansions. A basic formula for uniformizing counterterms is constructed by nesting an increasing number of extensions. Two successive extensions are shown to contain the counterterms for both secular terms and for singular perturbation terms. Simple examples are used to illustrate the method. A general constructive procedure is outlined to determine the counterterms from the nonuniformities arising in the direct perturbation expansion. A relationship is established between the secular perturbation counterterms and the singular perturbation counterterms. Finally, a brief review is given of the main results obtained so far and of the open problems.

Guido Sandri

Papers

The foundations of nonequilibrium statistical mechanics, II

Bernoulli enthalpy - A fundamental concept in the theory of sound

Fundamental Research in Turbulent Modeling.

Fundamental Research in Turbulent Modeling, Part 1. Theory. Part 2. Experiment.

Uniformization of Asymptotic Expansions