一维可压缩Euler方程组的两个模型

作者考察了一维可压缩Euler方程组的两个模型.利用特征分解和Gronwall不等式,首先得到具有几何结构且绝热指数γ=3的一维可压缩Euler方程组L~∞模的一致有界性.进一步,考虑当绝热指数γ=-1时,一维非等熵可压缩Euler方程组的Cauchy问题.在适当的假设下,得到该系统的整体经典解.     

On the Domain Dependence of Solutions to the Compressible Navier-Stokes Equations of an Isothermal Fluid

The aim of this paper is to study the behaviour of the variational solutions to the Navier-Stokes equations describing viscous compressible isothermal fluids with nonlinear stress tensors in a sequence of domains $\{\varOmega_{n}\} _{n=1}^{\infty}$ . The sequence converges in sense of the Sobolev-Orlicz capacity to domain Ω. We prove that the solutions of the equations in Ω _n converge to a solution of the respective equations in Ω. Moreover, The result can be applied to generalization of the existence result.     

Propagation of Density-Oscillations in Solutions to the Compressible Navier-Stokes-Poisson System

Concerning a bounded sequence of finite energy weak solutions to the compressible Navier-Stokes-Poisson system （denoted by CNSP）, which converges up to extraction of a subsequence, the limit system may not be the same system. By introducing Young measures as in [6, 15], the authors deduce the system （HCNSP） which the limit functions must satisfy. Then they solve this system in a subclass where Young measures are convex combinations of Dirac measures, to give the information on the propagation of density-oscillations. The results for strong solutions to （CNSP） （see Corollary 6.1） are also obtained.     

Zero Dissipation Limit to Rarefaction Waves for the 1-D Compressible Navier-Stokes Equations

The zero dissipation limit for the one-dimensional Navier-Stokes equations of compressible,isentropic gases in the case that the corresponding Euler equations have rarefaction wave solutions is investi...     

Global Existence and Convergence Rates of Smooth Solutions for the 3-D Compressible Magnetohydrodynamic Equations Without Heat Conductivity

In this paper, we are concerned with the global existence and convergence rates of the smooth solutions for the compressible magnetohydrodynamic equations without heat conductivity, which is a hyperbolic-parabolic system. The global solutions are obtained by combining the local existence and a priori estimates if H³-norm of the initial perturbation around a constant states is small enough and its L¹-norm is bounded. A priori decay-in-time estimates on the pressure, velocity and magnetic field are used to get the uniform bound of entropy. Moreover, the optimal convergence rates are also obtained.     

Exact Solutions of Compressible Flow Equations with Spherical Symmetry

In this paper, we construct spherically symmetric solutions of the equations of compressible flow, which are important in the theory of explosion waves in air, water, and other media. Following McVittie [ 1 ], we write a general solution form, in terms of velocity potential, as a product of a function of time and a function of a similarity variable. First, we find solutions to the equations of motion and continuity without reference to adiabatic or isentropic relation. These solutions are quite general and can be applied to nonadiabatic motions, such as the motions of interstellar gas clouds that lose energy by radiation. All the solutions found by McVittie [ 1 ] have linear velocity profile with respect to distance. We introduce a nonlinear form of the velocity function containing an arbitrary function of the similarity variable. Adiabatic conditions lead to a second-order ODE, which we discuss in some detail. We relate our work to the earlier investigations of Taylor [ 2 ], McVittie [ 1 ], and Keller [ 3 ].     

可压缩欧拉-泊松方程组平衡解的存在性

可压缩欧拉-泊松方程组描述的是具自引力势能气态星体内部气体的运动变化.对于满足质量守恒和能量守恒的一些速度场,本文在熵函数的光滑性较弱的条件下研究欧拉-泊松方程组平衡解的存在性.在本文中,作者应用变分方法得到6/5＜γ＜2时方程组平衡解的存在性结果.该结果减弱了关于非旋转星体欧拉-泊松方程组平衡解存在的条件,从而适用于更一般的物理环境.     

Measure-valued Solutions of the Euler Equations for Ideal Compressible Polytropic Fluids

The existence of global measure-valued solutions to the Euler equations describing the motion of an ideal compressible and heat conducting fluid is proved. The motion is considered in a bounded domain Ω⊂ℝ³ with impermeable boundary. The solution is a limit of an approximate solution obtained by adding the sixth-order elliptic operator in the equation of momentum.     

等熵可压Navier-Stokes-Poisson方程局部强解适定性

该文得到了三维情形等熵可压Navier-Stokes-Poisson方程局部强解的存在性、唯一性及稳定性. 重要的是,该文允许初始密度真空的存在. 首先用推广形式的Gronwall不等式得到了强解的局部存在性,然后得到了较弱条件下的唯一性,在证明唯一性的同时得到了稳定性.     

The Blow-up of Solutions for Two-Dimensional Irrotational Compressible Euler Equations

For two-dimensional irrotational compressible Euler equations with initial data where that is a small perturbation from a constant state, we prove that the first-order derivatives of ρ, υ blow-up at the blow-up time, while ρ, υ remain continuous. In particular, in the irrotational case we prove S. Alinhac's statement. Project supported bythe Tianyuan Foundation of China and Lab. of Math. for Nonlinear Problems. Fudan. Univ.     

Analytical Blowup Solutions to the Compressible Euler Equations with Time-depending Damping

In this paper, the analytical blowup solutions of the N-dimensional radial symmetric compressible Euler equations are constructed. Some previous results of the blowup solutions for the compressible Euler equations with constant damping are generalized to the time-depending damping case. The generalization is untrivial because that the damp coefficient is a nonlinear function of time t.

     

Convergence of Compressible Euler-Maxwell Equations to Compressible Euler-Poisson Equations

In this paper,the convergence of time-dependent Euler-Maxwell equations to compressible Euler-Poisson equations in a torus via the non-relativistic limit is studied. The local existence of smooth solutions to both systems is proved by using energy esti- mates for first order symmetrizable hyperbolic systems.For well prepared initial data the convergence of solutions is rigorously justified by an analysis of asymptotic expansions up to any order.The authors perform also an initial layer analysis for general initial data and prove the convergence of asymptotic expansions up to first order.     

粘性依赖密度的Navier-Stokes方程组的不连续解

该文研究了一类粘性系数依赖于密度的一维可压缩Navier-Stokes方程组的自由边界问题. 对初始密度是不连续的情形,证明了其解的局部存在性和唯一性. 其结果说明：不论初始密度的振荡幅度有多大,在某个时间段$[0,T]$上,气体内部不会产生真空状态,气体和真空的分界也是以有限速度传播的.     

Measure-valued Solutions of the Euler and Navier-Stokes Equations for Compressible Barotropic Fluids

The notion of a measure-valued solution for the Euler and the Navier-Stokes equations is introduced and its global in time existence is proved.     

Pathwise Solutions of the 2-D Stochastic Primitive Equations

In this work we consider a stochastic version of the Primitive Equations (PEs) of the ocean and the atmosphere and establish the existence and uniqueness of pathwise, strong solutions. The analysis employs novel techniques in contrast to previous works (Ewald et al. in Anal. Appl. (Singap.) 5(2):183–198, 2007; Glatt-Holtz and Ziane in Discrete Contin. Dyn. Syst. Ser. B 10(4):801–822, 2008) in order to handle a general class of nonlinear noise structures and to allow for physically relevant boundary conditions. The proof relies on Cauchy estimates, stopping time arguments and anisotropic estimates.     

可压磁流体方程组弱解轨迹的渐近行为(英文)

研究可压磁流体力学方程组弱解轨迹的渐近行为,流体受任意外力作用且流经的区域为三维有界区域.对绝热指数进行适当限制,得到了有限能量弱解的轨迹的渐近行为.