Semilinear Hyperbolic Systems and Equations with Singular Initial Data.
We discuss the definitions of singular solutions (in the form of integral identities) to systems of conservation laws such as shocks, δ-, δ’-, and -shocks (n = 2,3,...). Using these definitions, the Rankine-Hugoniot conditions for δ- and δ’-shocks are derived. The weak asymptotics method for the solution of the Cauchy problems admitting δ- and δ’-shocks is briefly described. The algebraic aspects of such singular solutions are studied. Namely, explicit formulas for flux-functions of singular solutions...
In this paper a mathematical model of a fluid flow in a tube with a valve and a pump is solved. The function of the valve is described in more detail than in [3], thus making the model more complete.
Soit , , , et les variables usuelles qui décrivent l’état d’un fluide en coordonnées eulériennes. Le domaine physique occupé par le fluide est a priori tout entier, mais peut être nul en dehors d’un compact . On choisit l’équation d’état d’un gaz parfait, , où est une constante. Le cas est celui du gaz mono-atomique.Dans la limite , les collisions sont rares et on est tenté d’approcher le mouvement des particules par un mouvement rectiligne uniforme : le champ de vitesse obéit alors...
We consider hyperbolic systems with time dependent coefficients and size or . We give some sufficient conditions in order the Cauchy Problem to be well-posed in and in Gevrey spaces.
We discuss the local existence and uniqueness of solutions of certain nonstrictly hyperbolic systems, with Hölder continuous coefficients with respect to time variable. We reduce the nonstrictly hyperbolic systems to the parabolic ones and by use of the Tanabe-Sobolevski’s method and the Banach scale method we construct a semi-group which gives a representation of the solution to the Cauchy problem.