Sobre flujos subsónicos alrededor de un obstáculo simétrico.
A mathematical model of a fluid flow in a single-piston pump is formulated and solved. Variation of pressure and rate of flow in suction and delivery piping respectively is described by linearized Euler equations for barotropic fluid. A new phenomenon is introduced by a boundary condition with discontinuous coefficient describing function of a valve. The system of Euler equations is converted to a second order equation in the space where is length of the pipe. The existence, unicity and stability...
Nous présentons dans cette note une nouvelle façon d’aborder les questions d’existence de solutions faibles pour certains problèmes d’interaction fluide-structure. Dans l’état actuel, cette approche permet de traiter le cas de solides rigides ou très faiblement déformables, immergés dans un fluide visqueux incompressible ou dans un fluide visqueux compressible dont l’évolution est isentropique.
This is a survey of some recent results on the existence of globally defined weak solutions to the Navier-Stokes equations of a viscous compressible fluid with a general barotropic pressure-density relation.
In [18]–[19], P.L. Lions studied (among others) the compactness and regularity of weak solutions to steady compressible Navier-Stokes equations in the isentropic regime with arbitrary large external data, in particular, in bounded domains. Here we investigate the same problem, combining his ideas with the method of decomposition proposed by Padula and myself in [29]. We find the compactness of the incompressible part of the velocity field and we give a new proof of the compactness of the “effective...
We review the main results concerning the global existence and the stability of solutions for some models of viscous compressible self-gravitating fluids used in classical astrophysics.
We study steady flow of a compressible heat conducting viscous fluid in a bounded two-dimensional domain, described by the Navier-Stokes-Fourier system. We assume that the pressure is given by the constitutive equation , where is the density and is the temperature. For , we prove existence of a weak solution to these equations without any assumption on the smallness of the data. The proof uses special approximation of the original problem, which guarantees the pointwise boundedness of the...
We prove the existence of solution in the class H²(Ω) × H¹(Ω) to the steady compressible Oseen system with slip boundary conditions in a two dimensional, convex domain with boundary of class . The method is to regularize a weak solution obtained via the Galerkin method. The problem of regularization is reduced to the problem of solvability of a certain transport equation by application of the Helmholtz decomposition. The method works under an additional assumption on the geometry of the boundary....
In according to a recent thermodynamic theory proposed by G. Grioli, we consider the growth of acceleration waves in a non viscous fluid. We determine the solutions for the growth of a plane or spherical wave advancing into the fluid in mechanical but not in thermal equilibrium.
In according to a recent thermodynamic theory proposed by G. Grioli we consider the growth of acceleration waves in a non viscous fluid. We determine the solutions for the growth of a plane or spherical wave advancing into the fluid in mechanical but not in thermal equilibrium.
Si dà un ulteriore contributo alla specificazione delle equazioni dinamiche di bilancio per una miscela di due fluidi non miscibili ma comprimibili.
Le but de cet article est de présenter quelques résultats mathématiques plus ou moins récents sur la théorie de l’existence globale en temps (solutions faibles et solutions fortes) pour les équations de Navier-Stokes compressibles en dimension supérieure ou égale à deux sans aucune hypothèse de symétrie sur le domaine et sans aucune hypothèse sur la taille des données initiales.