Envelope Method and More General New Global Structures of Solutions for Multi-dimensional Conservation Law

For the two-dimensional(2D)scalar conservation law,when the initial data contain two different constant states and the initial discontinuous curve is a general curve,then complex structures of wave interactions will be generated.In this paper,by proposing and investigating the plus envelope,the minus envelope,and the mixed envelope of 2D non-selfsimilar rarefaction wave surfaces,we obtain and the prove the new structures and classifications of interactions between the 2D non-selfsimilar shock wave and the rarefaction wave.For the cases of the plus envelope and the minus envelope,we get and prove the necessary and sufficient criterion to judge these two envelopes and correspondingly get more general new structures of 2D solutions.

Global Solutions and Interactions of Non-selfsimilar Elementary Waves for n-D Non-homogeneous Burgers Equation

We investigate the global structures of the non-selfsimilar solutions for n-dimensional(n-D) nonhomogeneous Burgers equation, in which the initial data has two different constant states, which are separated by a(n-1)-dimensional sphere. We first obtain the expressions of n-D shock waves and rarefaction waves emitting from the initial discontinuity. Then, by estimating the new kind of interactions of the related elementary waves,we obtain the global structures of the non-selfsimilar solutions, in which ingenious techniques are proposed to construct the n-D shock waves. The asymptotic behaviors with geometric structures are also proved.

Smooth Solution of Multi-dimensional Nonhomogeneous Conservation Law: Its Formula, and Necessary and Sufficient Blowup Criterion

In this paper, we are concerned with the necessary and sufficient condition of the global existence of smooth solutions of the Cauchy problem of the multi-dimensional scalar conservation law with source-term,where the initial data lies in W1,∞(Rn) ∩ C1(Rn). We obtain the solution formula for smooth solution, and then apply it to establish and prove the necessary and sufficient condition for the global existence of smooth solution. Moreover, if the smooth solution blows up at a finite time, the exact lifespan of the smooth solution can be obtained. In particular, when the source term vanishes, the corresponding theorem for the homogeneous case is obtained too. Finally, we give two examples as its applications, one for the global existence of the smooth solution and the other one for the blowup of the smooth solutions at any given positive time.

Structures of Interaction of Non-selfsimilar Elementary Waves for 2D Scalar Conservation Law with Two Initial Discontinuities

In this paper,we investigate the global solution and the structures of interaction between two dimensional non-selfsimilar shock wave and rarefaction wave of general two-dimensional scalar conservation law in which flux functions f(u)and g(u)do not need to be convex,and the initial value contains three constant states which are respectively separated by two general initial discontinuities.When initial value contains three constant states,the cases of selfsimilar shock wave and rarefaction wave had been studied before,but no results of the cases of neither non-selfsimilar shock wave or non-selfsimilar rarefaction wave.Under the assumption that Condition H which is generalization of one dimensional convex condition,and some weak conditions of initial discontinuity,according to all the kinds of combination of elementary waves respectively staring from two initial discontinuities,we get four cases of wave interactions as S+S,S+R,R+S and R+R.By studying these interactions between non-selfsimilar elementary waves,we obtain and prove all structures of non-selfsimilar global solutions for all cases.

The Singular Structure of Non-selfsimilar Global Solutions of n Dimensional Burgers Equation

We investigate the singular structure for n dimensional non-selfsimilar global solutions and interaction of non-selfsimilar elementary wave of n dimensional Burgers equation, where the initial discontinuity is a n dimensional smooth surface and initial data just contain two different constant states, global solutions and some new phenomena are discovered. An elegant technique is proposed to construct n dimensional shock wave without dimensional reduction or coordinate transformation.

Envelope and Classification of Global Structures of Solutions for a Class of Two-dimensional Conservation Laws

Two-dimensional Riemann problem for scalar conservation law are investigated and classification of global structure for its nomselfsimilar solution is given by analysis of structure and classification of envelope for non-selfsimilar 2D rarefaction wave. Initial data has two different constant states which are separated by initial discontinuity. We propose the concepts of plus envelope, minus envelope and mixed envelope, and some new structures and evolution phenomena are discovered by use of these concepts.

Non-selfsimilar Global Solutions and Their Structure for the Multi-dimensional Combustion Models

We investigate the Chapman-Jouguet model in multi-dimensional space, and construct explicitly its non-selfsimilar Riemann solutions. By the method we apply in this paper, general initial discontinuities can be dealt with, even for complex interaction of combustion waves. Furthermore, we analyze the way in which the area of unburnt gas shrinks.

Reflection and Refraction of Waves Across an Interface of Two-phase Flow

We investigate a hyperbolic system of one-dimensional isothermal fluid with liquid-vapor phase transition.The refraction-reflection phenomena are intensively analyzed when elementary waves travel across the two-phase interface.We apply the characteristic method and hodograph transform of Riemann to reduce the nonlinear PDEs to a concise form.Specially for the case of incident rarefaction wave,reduced linear equations are convenient to solve by Laplace transform.Then an integral formula in wave interaction region is derived in this paper,instead of the hypergeometric functions solutions for non-isothermal polytropic gases.It is also observed that when incident waves travel from the vapor phase to the liquid phase,the refracted waves must be accelerated and move forward.

Riemann Problems for Three-dimensional Combustion Models

We investigate Chapman-Jouguet models in three-dimensional space by means of generalized char- acteristic analysis. The interaction of detonation, shock waves and contact discontinuity is discussed intensively in this paper. If contact discontinuity appears, the structure of global solutions becomes complex. We deal with this problem when strength of detonation is small.