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1.
Gerhard Rein 《Archive for Rational Mechanics and Analysis》2003,168(2):115-130
We construct steady states of the Euler-Poisson system with a barotropic equation of state as minimizers of a suitably defined
energy functional. Their minimizing property implies the non-linear stability of such states against general, i.e., not necessarily
spherically symmetric, perturbations. The mathematical approach is based on previous stability results for the Vlasov-Poisson
system by Y. Guo and G. Rein, exploiting the energy-Casimir technique. The analysis is conditional in the sense that it assumes the existence of solutions to the initial value problem for the Euler-Poisson system which preserve mass and energy. The
relation between the Euler-Poisson and the Vlasov-Poisson system in this context is also explored.
(Accepted January 30, 2003)
Published online May 14, 2003
Communicated by P.J. Holmes 相似文献
2.
We consider a space-periodic version of the relativistic Vlasov-Maxwell system describing a collisionless plasma consisting of electrons and positively charged ions. As our main result, we prove that certain spacially homogeneous stationary solutions are nonlinearly stable. To this end we also establish global existence of weak solutions to the corresponding initial value problem. Our investigation is motivated by a corresponding result for the Vlasov-Poisson system, cf. [1, 14]. 相似文献
3.
We study an optimal inequality which relates potential and kinetic energies in an appropriate framework for bounded solutions of the Vlasov-Poisson (VP) system. Optimal distribution functions, which are completely characterized, minimize the total energy. From this variational approach, we deduce bounds for the kinetic and potential energies in terms of conserved quantities (mass and total energy) of the solutions of the VP system and a nonlinear stability result. Then we apply our estimates to the study of the large-time asymptotics and observe two different regimes. 相似文献
4.
We propose a Bhatnagar–Gross–Krook (BGK) kinetic model in which the collision frequency is a linear combination of polynomials in the velocity variable. The coefficients of the linear combination are determined so as to enforce proper relaxation rates for a selected group of moments. The relaxation rates are obtained by a direct numerical evaluation of the full Boltzmann collision operator. The model is conservative by construction. Simulations of the problem of spatially homogeneous relaxation of hard spheres gas show improvement in accuracy of controlled moments as compared to solutions obtained by the classical BGK, ellipsoidal-statistical BGK and the Shakhov models in cases of strong deviations from continuum. 相似文献
5.
We consider the initial-value problem for a system of coupled Boussinesq equations on the infinite line for localised or sufficiently rapidly decaying initial data, generating sufficiently rapidly decaying right- and left-propagating waves. We study the dynamics of weakly nonlinear waves, and using asymptotic multiple-scale expansions and averaging with respect to the fast time, we obtain a hierarchy of asymptotically exact coupled and uncoupled Ostrovsky equations for unidirectional waves. We then construct a weakly nonlinear solution of the initial-value problem in terms of solutions of the derived Ostrovsky equations within the accuracy of the governing equations, and show that there are no secular terms. When coupling parameters are equal to zero, our results yield a weakly nonlinear solution of the initial-value problem for the Boussinesq equation in terms of solutions of the initial-value problems for two Korteweg-de Vries equations, integrable by the Inverse Scattering Transform. We also perform relevant numerical simulations of the original unapproximated system of Boussinesq equations to illustrate the difference in the behaviour of its solutions for different asymptotic regimes. 相似文献
6.
We consider a very general class of delayed reaction–diffusion equations in which the reaction term can be non-monotone as well as spatially non-local. By employing comparison technique and a dynamical system approach, we study the global asymptotic behavior of solutions to the equation subject to the homogeneous Dirichlet condition. Established are threshold results and global attractiveness of the trivial steady state, as well as the existence, uniqueness and global attractiveness of a positive steady state solution to the problem. As illustrations, we apply our main results to the local delayed diffusive Mackey–Glass equation and the nonlocal delayed diffusive Nicholson blowfly equation, leading to some very sharp results for these two particular models. 相似文献
7.
A widespread belief in the study of granular flow is the existence of “homogeneous cooling states”, i.e., self-similar solutions which would attract all solutions, faster than the equilibrium solution does. In most cases, the existence of these self-similar solutions is an open problem. Here we consider a one-dimensional model, which has been used for some years, and for which simple self-similar solutions do exist. However, we prove that the approximation is quite poor. Our proof makes use of the powerful and simple tools of mass transportation, and exploits the structure of the evolution equation, seen as a nonlinear transport equation. 相似文献
8.
We establish new conditions under which the initial-value problem for a system of linear second-order differential equations
with argument deviations has a unique solution, which depends monotonically on additive perturbations of the problem.
__________
Translated from Neliniini Kolyvannya, Vol. 9, No. 4, pp. 535–547, October–December, 2006. 相似文献
9.
《Fluid Dynamics Research》1994,13(3-4):167-195
In this paper infinite plane Couette flow in a viscous incompressible fluid is considered subject to general three-dimensional perturbations and the equations of motion are linearized. Furthermore, initial-value problems are posed and a set of closed-form solutions are obtained for a variety of conditions, such as the system under the influence of: (i) a mass source; (ii) an external force; or (iii) initial vorticity. The result is a knowledge of both the early transient dynamics and the near spatial field behavior, as well as the state after a long time and the far field behavior. It is shown that the solutions can be considered as fundamental (in the sense that source-sink solutions are regarded fundamental for irrotational motion) and therefore are useful in analyzing other boundary-value, initial-value problems where the basic flow can be synthesized from piece-wise linear (constant shear) variations. To this end a generalized Green's function for the system is determined. 相似文献
10.
In this paper, the spatiotemporal patterns of a reaction–diffusion substrate–inhibition chemical Seelig model are considered. We first prove that this parabolic Seelig model has an invariant rectangle in the phase plane which attracts all the solutions of the model regardless of the initial values. Then, we consider the long time behaviors of the solutions in the invariant rectangle. In particular, we prove that, under suitable “lumped parameter assumption” conditions, these solutions either converge exponentially to the unique positive constant steady states or to the spatially homogeneous periodic solutions. Finally, we study the existence and non-existence of Turing patterns. To find parameter ranges where system does not exhibit Turing patterns, we use the properties of non-constant steady states, including obtaining several useful estimates. To seek the parameter ranges where system possesses Turing patterns, we use the techniques of global bifurcation theory. These two different parameter ranges are distinguished in a delicate bifurcation diagram. Moreover, numerical experiments are also presented to support and strengthen our analytical analysis. 相似文献
11.
We prove the existence and nonlinear stability of steady states of the Vlasov-Poisson system in the stellar dynamics case. The steady states are obtained as minimizers of an energy-Casimir functional from which fact their dynamical stability is deduced. The analysis applies to some of the well-known polytropic steady states, but it also considerably extends the class of known steady states. 相似文献
12.
Gerhard Rein 《Archive for Rational Mechanics and Analysis》2002,161(1):27-42
Certain steady states of the Vlasov-Poisson system can be characterized as minimizers of an energy-Casimir functional, and this fact implies a non-linear stability property of such steady states. In previous investigations by Y. Guo and G. Rein, stability was obtained only with respect to spherically symmetric perturbations. In the present investigation we show how to remove this non-physical restriction. 相似文献
13.
Jürgen Batt Philip J. Morrison Gerhard Rein 《Archive for Rational Mechanics and Analysis》1995,130(2):163-182
Rigorous results on the stability of stationary solutions of the Vlasov-Poisson system are obtained in the contexts of both plasma physics and stellar dynamics. It is proved that stationary solutions in the plasma physics (stellar dynamics) case are linearly stable if they are decreasing (increasing) functions of the local, i.e., particle, energy. The main tool in the analysis is the free energy, a conserved quantity of the linearized system. In addition, an appropriate global existence result is proved for the linearized Vlasov-Poisson system and the existence of stationary solutions which satisfy the above stability condition is established. 相似文献
14.
Thomas Brand Markus Kunze Guido Schneider Thorsten Seelbach 《Archive for Rational Mechanics and Analysis》2004,171(2):263-296
We consider solutions bifurcating from a spatially homogeneous equilibrium under the assumption that the associated linearization possesses a continuous spectrum up to the imaginary axis, for all values of the bifurcation parameter, and that a pair of imaginary eigenvalues crosses the imaginary axis. For a reaction-diffusion-convection system we investigate the nonlinear stability of the trivial solution with respect to spatially localized perturbations, prove the occurrence of a Hopf bifurcation and the nonlinear stability of the bifurcating time-periodic solutions, again with respect to spatially localized perturbations. 相似文献
15.
Xiao-Biao Lin 《Journal of Dynamics and Differential Equations》1996,8(3):325-372
We discuss a diffusively perturbed predator-prey system. Freedman and Wolkowicz showed that the corresponding ODE can have a periodic solution that bifurcates from a homoclinic loop. When the diffusion coefficients are large, this solution represents a stable, spatially homogeneous time-periodic solution of the PDE. We show that when the diffusion coefficients become small, the spatially homogeneous periodic solution becomes unstable and bifurcates into spatially nonhomogeneous periodic solutions. The nature of the bifurcation is determined by the twistedness of an equilibrium/homoclinic bifurcation that occurs as the diffusion coefficients decrease. In the nontwisted case two spatially nonhomogeneous simple periodic solutions of equal period are generated, while in the twisted case a unique spatially nonhomogeneous double periodic solution is generated through period-doubling. 相似文献
16.
Wenxian Shen 《Journal of Dynamics and Differential Equations》2011,23(1):1-44
The current paper is devoted to the study of traveling wave solutions of spatially homogeneous monostable reaction diffusion
equations with ergodic or recurrent time dependence, which includes periodic and almost periodic time dependence as special
cases. Such an equation has two spatially homogeneous and time recurrent solutions with one of them being stable and the other
being unstable. Traveling wave solutions are a type of entire solutions connecting the two spatially homogeneous and time
recurrent solutions. Recently, the author of the current paper proved that a spatially homogeneous time almost periodic monostable
equation has a spreading speed in any given direction. This result can be easily extended to monostable equations with recurrent
time dependence. In this paper, we introduce generalized traveling wave solutions for time recurrent monostable equations
and show the existence of such solutions in any given direction with average propagating speed greater than or equal to the
spreading speed in that direction and non-existence of such solutions of slower average propagating speed. We also show the
uniqueness and stability of generalized traveling wave solutions in any given direction with average propagating speed greater
than the spreading speed in that direction. Moreover, we show that a generalized traveling wave solution in a given direction
with average propagating speed greater than the spreading speed in that direction is unique ergodic in the sense that its
wave profile and wave speed are unique ergodic, and if the time dependence of the monostable equation is almost periodic,
it is almost periodic in the sense that its wave profile and wave speed are almost periodic. 相似文献
17.
黄永念 《应用数学和力学(英文版)》1992,13(12):1115-1120
In this paper by using tensor analysis we give the explicit expressions of the solution of the initial-value problem of homogeneous linear differential equations with constant coefficients and the n th-order homogeneous linear differential equation with constant coefficients. In fact, we give the general formula for calculating the elements of the matrix exp[At]. We also give the results when the characteristic equation has the repeated roots. The present method is simpler and better than the other methods. 相似文献
18.
《Fluid Dynamics Research》1994,13(3-4):153-166
The initial-value problem of shallow-water waves due to an oscillatory surface stress distribution on a homogeneous rotating ocean is solved by the method of integral transforms. For the wave integral, an asymptotic analysis is given which is uniform across the line produced by the coalescing of the pole and the stationary point of the wave spectrum; the result, unlike previous findings, is non-singular when the circular frequency of oscillation equals the Coriolis parameter. Some limiting cases of interest are deduced and the asymptotic envelope of the progressive waves at the surface is illustrated graphically. 相似文献
19.
Huang Yong-nian 《应用数学和力学(英文版)》1992,13(12):1115-1120
In this paper by using tensor analysis we give the explicit expressions of the solution of the initial-value problem of homogeneous
linear differential equations with constant coefficients and the n th-order homogeneous linear differential equation with
constant coefficients. In fact, we give the general formula for calculating the elements of the matrix exp [At]. We also give the results when the characteristic equation has the repeated roots. The present method is simpler and better
than, the other methods. 相似文献
20.
Analytical solutions for thermal forcing vortices in boundary layer and its applications 总被引:4,自引:0,他引:4
Using the Boussinesq approximation, the vortex in the boundary layer is assumed to be axisymmetrical and thermal-wind balanced system forced by diabatic heating and friction, and is solved as an initial-value problem of linearized vortex equation set in cylindrical coordinates. The impacts of thermal forcing on the flow field structure of vortex are analyzed. It is found that thermal forcing has significant impacts on the flow field structure, and the material representative forms of these impacts are closely related to the radial distribution of heating. The discussion for the analytical solutions for the vortex in the boundary layer can explain some main structures of the vortex over the Tibetan Plateau. 相似文献