Solitary waves in dusty plasmas with variable dust charge and two temperature ions

Propagation of nonlinear waves in dusty plasmas with variable dust charge and two temperature ions is analyzed. The Kadomtsev–Petviashivili (KP) equation is derived by using the reductive perturbation theory. A Sagdeev potential for this system has been proposed. This potential is used to study the stability conditions and existence of solitonic solutions. Also, it is shown that a rarefactive soliton can be propagates in most of the cases. The soliton energy has been calculated and a linear dispersion relation has been obtained using the standard normal-modes analysis. The effects of variable dust charge on the amplitude, width and energy of the soliton and its effects on the angular frequency of linear wave are discussed too. It is shown that the amplitude of solitary waves of KP equation diverges at critical values of plasma parameters. Solitonic solutions of modified KP equation with finite amplitude in this situation are derived.     

Study of the dust acoustic waves in a magnetized dusty plasma with many different dust grains

The nonlinear dust waves in a magnetized dusty plasma with many different dust grains are analytically investigated. New analytical solutions for the governing equation of this system have been obtained for the dust acoustic waves in a dusty plasma for the first time. We derive exact mathematical expressions for the general case of the nonlinear dust waves in magnetized dusty plasma which contains different dust grains.     

Analytical study of nonlinear dust acoustic waves in two-dimensional dust plasma with vortex-like ion distribution

The nonlinear dust acoustic waves in two-dimensional dust plasma with vortex-like ion distribution are analytically investigated by using the formally variable separation approach. New analytical solutions for the governing equation of this system have been obtained for dust acoustic waves in a dust plasma for the first time. We derive exact analytical expressions for the general case of the nonlinear dust acoustic waves in two-dimensional dust plasma with vortex-like ion distribution.     

On the wave interaction in a charged fluid with Hall and ion slip-currents

Summary The evolution of non linear small perturbations in a charged fluid with generalized Ohm's law is considered, pointing out the possibility of effects due to interaction between different waves. Following the perturbative reductive methods, some phase functions for studying interaction are introduced. A suitable hypothesis on their evolution permits us to prove that the amplitudes of the first order perturbation obey Burgers-like equations, in which the dissipative terms are not influenced by the Hall effect.

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Riassunto Si studia l'evoluzione di piccole perturbazioni in un sistema M.F.D. con legge di Ohm generalizzata, prendendo in considerazione gli effetti della mutua interazione tra onde appartenenti a differenti famiglie di caratteristiche. Mediante tecniche di tipo perturbativo riduttivo e con l'introduzione di opportune funzioni di fase, si mostra che le ampiezze delle perturbazioni sono regolate, in prima approssimazione, da equazioni del tipo di Burgers in cui i termini dissipativi non dipendono dall'effetto Hall.

     

On the waves in two superposed liquids in the presence of a wall

An exact analysis, based on a simple reduction procedure, is described in this work for finding the linear solution of the normally incident incoming waves in the presence of surface tension (ST) in two liquids, where the liquids are bounded on the left by a rigid vertical wall. Analytical expressions for the velocity potentials in each of the two liquids are obtained here assuming the lower liquid to be of uniform finite depth and the upper liquid to be of uniform finite height.     

Effects of the dust charge variation and non-thermal ions on multi-dimensional dust acoustic solitary structures in magnetized dusty plasmas

The combined effects of both adiabatic dust charge variation and non-thermally (fast) distributed ions on dust acoustic solitary structures are studied in a magnetized dusty plasmas consisting of the negatively and variably charged hot dust fluid, Boltzmann distributed electrons and non-thermally distributed ions. By using the reductive perturbation method, we derive the Korteweg-de Vries (KdV) equation governing the dust acoustic solitary waves. It is shown that the dust charge variation and the presence of non-thermally distributed ions would modify the nature of dust acoustic solitary structures significantly and may excite both dust acoustic solitary holes (soliton with a density dip) and positive solitons (soliton with a density hump).     

Semi-analytical study of variable charge dust acoustic solitary waves in a dusty plasma with a q-nonextensive ion velocity distribution

An attempt is made to study variable charge dust acoustic (DA) solitons within the theoretical framework of the Tsallis statistical mechanics. The correct nonextensive ion charging current is presented for the first time based on the orbit motion limited (OML) approach. The variable dust charge is then expressed in terms of the Lambert function and we take advantage of this transcendental function to investigate nonlinear localized DA waves in a charge varying dusty plasma with nonextensive ions more rigorously. Our results reveal that the ion nonextensivity makes the dust acoustic solitary structure more spiky. As the ions deviate from their thermodynamic equilibrium, the dust grain charge becomes least negative and the dust accumulation more effective. In addition, the nonextensive character of the ions contributes to the electron depletion. The latter is more pronounced as the ions evolve far away from their thermal equilibrium. Our results should help in providing a good fit between theoretical and experimental results.     

Theoretical results of the dust acoustic waves in a magnetized dusty plasma with different dust particles

In this paper, the nonlinear dust acoustic waves (DAW) in a magnetized dusty plasmas with different dust grains are analytically investigated. New analytical solutions of the governing equation for this system have been obtained for the first time. The exact mathematical expressions of the nonlinear dust waves have been canvassed for the general case in magnetized dusty plasma containing different dust particles.     

On the velocity of separation between two successive traveling waves in the asymptotics of the solution to the Cauchy problem for a Burgers-type equation

An upper bound on the distance between the centers of two successive traveling waves occurring in the asymptotics of the solution to the Cauchy problem for a Burgers-type equation is established under generic conditions. Taking into account a previously established lower bound, an asymptotically sharper estimate is derived.     

On blowup of solutions to a system of equations of ion sound waves in plasma

Some model system of equations is examined that comprises two sixth order equations of Sobolev type with the second order time derivative. This system describes explosive instability in plasma accounting for the strong space-time dispersion and nonlinear dependence of polarizability on the electric field strength. The case of the so-called focusing medium is also considered.     

Asymptotic representation of surface waves in the form of two traveling burgers waves

Chair of General Mathematics, Department of Computational Mathematics and Cybernetics, M. V. Lomonosov Moscow State University. Translated from Funktsional'nyi Analiz i Ego Prilozheniya, Vol. 29, No. 3, pp. 25–40, July–September, 1995.     

Propagation of shear waves in a poroelastic layer constrained between two elastic layers

In this paper, we investigated the propagation of shear waves in a transversely isotropic poroelastic layer constrained between two elastic layers. Following Biot’s theory, the dispersion equation for shear waves in this structure was derived. The numerical values on the dimensionless phase velocities are calculated and presented graphically to illustrate the dependences upon geometry, anisotropy and porosity comparatively. It is observed that the phase velocities increase with the increase of the porosity and the decrease of the anisotropy. In addition, the geometry in this structure has a significant effect on the phase velocity of the shear waves.     

On the relationship between love modes and the set of supercritically reflected waves

Considering the Love problem as an example, we derive relations connecting the following two exact integral representations of its solution: one explicitly involving both damped and undamped modes (residues at the roots of the dispersion equation of the problem) and the other based on expanding the interference field into a series of a geometric progression. In the latter case, to each such summand a generalized ray of a wave of certain multiplicity propagating in the layer can be put into correspondence. By using the methods of contour integrals, a correspondence between the set of multiple waves and interference modes is established. Bibliography: 1 title. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 214, 1994, pp. 200–209. Translated by T. N. Surkova.     

On the gap between two classes of analytic functions

Two large classes of analytic functions are defined, so that one contains the other. Sharp coefficient bounds for quadratic polynomials falling in the gap between these two classes are given.     

On the thermal runaway of variable viscosity flows between concentric cylinders

In this paper we use asymptotic methods to analyse the boundary layer flow of a Newtonian fluid between concentric cylinders. The temperature distribution up to the time of thermal runaway is obtained. We give conditions for occurrence of thermal runaway.

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Résumé Nous avons appliqué dans cette étude les méthodes asymptotiques pour analyser le flux de la couche limite d'un liquide Newtonien entre deux cylindres concentriques. Nous avons obtenu la répartition de température jusqu'au moment où le circuit thermique se produit. Nous avons établi des conditions qui entraînent cette saute de température.

     

Reflection and transmission of elastic waves in the multilayered orthotropic couple-stressed plates sandwiched between two elastic half-spaces

In this paper, a high efficient computational approach, the extended Legendre orthogonal polynomial method (LOPM) is provided to investigate the reflection and transmission of elastic waves in orthotropic couple-stress layered plates sandwiched between two elastic half-spaces. In this approach, the anisotropic couple-stress theory is introduced into the LOPM to calculate the reflection and transmission coefficients of the orthotropic interlayers. The stress components, couple-stress components, rotation vectors and governing equations are derived in terms of the Legendre orthogonal polynomial. The present method does not require calculations of the displacement solutions of each partial wave in anisotropic multilayered microstructures, but expands the displacement vector of each layer into a Legendre orthogonal polynomial series with the expansion coefficients to be calculated. The incident P wave and SH wave are calculated, respectively. The effects of length scale parameters in three different directions are studied. It is found that the reflection and transmission coefficients of the incident P wave are only related to the length scale parameter in the z direction. For incident SH wave, the influence of the length scale parameter along the thickness direction is much more significant than that of the length scale parameter in the y direction.     

On the theory of the third-order equation with multiple characteristics containing the second time derivative

We construct a fundamental solution of the third-order equation with multiple characteristics containing the second time derivative, establish the estimates valid for large values of the argument, and study some properties of fundamental solutions necessary for the solution of boundary-value problems.     

On nonlinear dynamics of interacting populations: Coupled kink waves in a system of two populations

We discuss a nonlinear model of the spatial–time interaction among populations which reproduction and intensity of interaction depend on their spatial density. For the particular case of two populations with constant growth rates and competition coefficients we obtain analytical nonlinear waves of kink kind. The kinks are connected to propagation of the deviations from the stationary densities corresponding to fixed points in the phase space of the population densities. The kinks are coupled, i.e. the changes of the densities of the two populations are synchronous. Coupled kink solutions are obtained also for the general case of variable growth rates and variable coefficients of interactions.