Nonlinear Energy Exchange Research Articles

Three-wave coupling coefficients for magnetized plasmas with pressure anisotropy

In order to find the equations for the nonlinear energy exchange between low-frequency waves in magnetized plasmas in the presence of pressure anisotropy, we start from the Chew–Goldberger–Low equations, the isothermal MHD equations, as well as a new hybrid system of equations. The coupling coefficients describing the interaction between two Alfvén waves and one magnetosonic wave as well as the interaction between two magnetosonic waves and one Alfvén wave are deduced.

Nonlinear vibration-translation energy exchange in a gas of partially dissociated molecules

It is shown, the partial dissociation of vibrationally excited molecules may lead to the nonlinear behaviour of the characteristic time of the vibrational-translational energy exchange (the time of the VT energy exchange depends on the energy of the vibrational excitation).

Multiple Fröhlich coherent states in biological systems: Computer simulation

Computer simulation of the energy storage in the band of normal modes with energy supply based on the kinetic equation with nonlinear (parametric) energy exchange terms indicates the possibility of the multiple Fröhlich coherent states excitation. It is mainly connected with the non-uniform transmission probabilities ξ of the combined emission-absorption processes between vibration modes. The effect of the coherent states changes on the long-range interaction forces and cancer cell migration is discussed.

Simulation studies of the basic non-linear effects of wave-energy conversion by an overtopping water-column

Several forms of wave-energy devices are currently being developed which incorporate oscillating ducted-flows. A method of extracting energy from such flows has been suggested whereby fluid is allowed to spill over from the top end of the duct during some portion of the oscillatory cycle into an elevated reservoir from whence it is directed through a low-head turbine. A mathematical model of this energy conversion system has been derived for simulation on a digital computer; and the results of the analysis are presented here in terms of the efficiency of operation relative to the optimum linear case. The simulation is repeated for a wide range of input conditions and operating parameters. The conclusions drawn from this work may be seen to have a wider application in the field of non-linear energy exchange in resonant mechanical systems.

Experiments in Atmospheric Predictability: Part I. Initialization

Abstract Predictability experiments are carried out with a divergent barotropic model that describes the evolution of quasi-geostrophic planetary waves and high-frequency gravity-inertia waves. Error growth, relative to a model-determined control state, is initiated by an initialization procedure that is not compatible with the model equations. An analysis of error growth due to improper representation of the physics incorporated in prediction models is also carried out with the present model. The error growth rate and the range of predictability determined from these experiments, based on a simple triad solution of the nonlinear forecast equation, compare very well with the results from experiments carried out with multi-level numerical models. The mechanism of predictability decay by nonlinear energy exchange is shown to differ from the corresponding mechanism discussed by Lorenz and Leith, which is based on a model of two-dimensional turbulence.

Barotropic Scale Interactions in the Tropical Upper Troposphere During the Northern Summer

A semi-spectral numerical model is used to investigate the nonlinear interactions between quasi-stationary long waves and transient synoptic waves in the tropical upper troposphere. Results from a long-term integration of this model show that nonlinear barotropic energy exchange between large-scale quasi-stationary forced waves and transient synoptic-scale waves is important in producing several features of the tropical upper tropospheric general circulation. In particular, the development of the small-scale waves and vortices often present in the mid-oceanic troughs and the disturbances observed by Krishnamurti which form along the easterly jet over the Indian Ocean is shown to be due to scale interactions involving short-term nonlinear barotropic instability. This nonlinear transfer of energy to smaller scales of motion acts as a damping mechanism to the large-scale forced circulation.

On Scale Interactions in the Tropics During Northern Summer

Abstract Results of computations of energy exchanges between waves and waves and between waves and zonal flows (for a tropical belt 15S to 15N at 200 mb for northern summer) are presented in this paper. These exchanges are 92-day averages. The procedure for calculations is essentially that proposed by Saltzman. The main results of this study are: Zonal wavenumber 1 appears to be a major energy source for the tropics. In general, one of two other waves interacting with wavenumber 1 gains energy. Wavenumber 1 also supplies energy to the zonal flows in the mean. Thus, it has a stabilizing influence on the zonal flows. On the other hand, zonal flows are unstable and lose energy to shorter waves, especially around wavenumber 8. In this paper we also discuss some details of the nonlinear wave-wave energy exchanges.