Modal interactions and energy transfers in isotropic turbulence as predicted by local energy transfer theory

1992 ◽  
Vol 10 (4-6) ◽  
pp. 499-526 ◽  
Author(s):  
V Shanmugasundaram
Keyword(s):  
Energy Transfer ◽  
Isotropic Turbulence ◽  
Local Energy ◽  
Modal Interactions ◽  
Transfer Theory ◽  
Energy Transfers

Energy Transfer in a Linear Turbulence Model

2018 ◽  
Author(s):  
Bendegúz Dezső Bak ◽  
Tamás Kalmár-Nagy
Keyword(s):  
Energy Transfer ◽  
Energy Spectrum ◽  
Isotropic Turbulence ◽  
Mechanistic Model ◽  
Viscous Friction ◽  
Scaling Exponent ◽  
Engineering Systems ◽  
Simple Method ◽  
The Masses ◽  
Binary Tree Structure

Energy transfer is present in many natural and engineering systems which include different scales. It is important to study the energy cascade (which refers to the energy transfer among the different scales) of such systems. A well-known example is turbulent flow in which the kinetic energy of large vortices is transferred to smaller ones. Below a threshold vortex scale the energy is dissipated due to viscous friction. We introduce a mechanistic model of turbulence which consists of masses connected by springs arranged in a binary tree structure. To represent the various scales, the masses are gradually decreased in lower levels. The bottom level of the model contains dampers to provide dissipation. We define the energy spectrum of the model as the fraction of the total energy stored in each level. A simple method is provided to calculate this spectrum in the asymptotic limit, and the spectra of systems having different stiffness distributions are calculated. We find the stiffness distribution for which the energy spectrum has the same scaling exponent (−5/3) as the Kolmogorov spectrum of 3D homogeneous, isotropic turbulence.

Model for Energy Transfer in Isotropic Turbulence

1962 ◽  
Vol 5 (5) ◽  
pp. 583 ◽  
Author(s):  
Robert H. Kraichnan ◽  
Edward A. Spiegel
Keyword(s):  
Energy Transfer ◽  
Isotropic Turbulence

Un exemple d'isomérisation radicalaire en chaînes: la photoinduction de l'isomérisation cis–trans de la pentène-3 one-2

1977 ◽  
Vol 55 (22) ◽  
pp. 3915-3926 ◽  
Author(s):  
Armel Rioual ◽  
André Deflandre ◽  
Jacques Lemaire
Keyword(s):  
Energy Transfer ◽  
Quantum Yields ◽  
Unsaturated Ketone ◽  
Chain Process ◽  
Triplet Energy ◽  
Low Concentrations ◽  
Energy Transfers ◽  
Donor And Acceptor ◽  
A Chain ◽  
Triplet Energy Transfer

Mechanisms of the photosensitized cis–trans photoisomerization of 3-penten-2-one which do not imply only classical triplet–triplet energy transfer are proposed; they are based upon measurements of the variations of initial quantum yields of isomerization with the initial donor and acceptor concentrations, the wavelength of excitation, and the nature of the donor and of the solvent. Carbonyl donors (acetophenone, benzophenone, acetone) induce a radical isomerization by a chain process in reducing solvents; the example of acetophenone is specially interesting. In solvents in which the donor is not photoreduced (as benzene or CCl4) classical triplet–triplet energy transfers occur. Sensitization with aromatic donors (benzene, mesitylene) proceeds through triplet–triplet energy transfer at low concentrations of the acceptor. At higher concentrations of acceptor, an exciplex is formed between the ketone and the aromatic in its singlet excited state; this exciplex is deactivated by dissociation and by causing the isomerization of the α,β-unsaturated ketone.

scholarly journals Internal Energy Transfer in Dynamical Behavior of Slightly Curved Shear Deformable Microplates

2015 ◽  
Vol 11 (4) ◽  
Author(s):  
Mergen H. Ghayesh ◽  
Hamed Farokhi ◽  
Gursel Alici
Keyword(s):  
Energy Transfer ◽  
Internal Energy ◽  
Couple Stress Theory ◽  
Dynamical Behavior ◽  
Shear Deformation Theory ◽  
Initial Imperfection ◽  
Modal Interactions ◽  
Initial Curvature ◽  
Out Of Plane ◽  
Transfer Mechanisms

This paper investigates the internal energy transfer and modal interactions in the dynamical behavior of slightly curved microplates. Employing the third-order shear deformation theory, the microplate model is developed taking into account geometric nonlinearities as well as the modified couple stress theory; the initial curvature is modeled by an initial imperfection in the out-of-plane direction. The in-plane displacements and inertia are retained, and the coupled out-of-plane, rotational, and in-plane motion characteristics are analyzed. Specifically, continuous models are developed for kinetic and potential energies as well as damping and external works; these are balanced and reduced via Lagrange's equations along with an assumed-mode technique. The reduced-order model is then solved numerically by means of a continuation technique; stability analysis is performed by means of the Floquet theory. The possibility of the occurrence of modal interactions and internal energy transfers is verified via a linear analysis on different natural frequencies of the system. The nonlinear resonant response of the system is obtained for the cases with internal energy transfer, and energy transfer mechanisms are analyzed; as we shall see, the presence of an initial curvature affects the system dynamics substantially. The importance of taking into account small-size effects is also shown by discovering this fact that both the linear and nonlinear internal energy transfer mechanisms are shifted substantially if this effect is ignored.

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