Stationary solutions to the equations of dynamics of mixtures of heat-conductive compressible viscous fluids

We consider the equations describing the three-dimensional steady motions of binary mixtures of heat-conductive compressible viscous fluids. An existence theorem for the boundary value problem that corresponds to flows in a bounded domain is proved in the class of weak generalized solutions.     

Evolution free boundary problem for equations of viscous compressible heat‐conducting capillary fluids

In the paper the global motion of a viscous compressible heat conducting capillary fluid in a domain bounded by a free surface is considered. Assuming that the initial data are sufficiently close to a constant state and the external force vanishes we prove the existence of a global‐in‐time solution which is close to the constant state for any moment of time. The solution is obtained in such Sobolev–Slobodetskii spaces that the velocity, the temperature and the density of the fluid have $W_2^{2+\alpha,1+\alpha/2}$\nopagenumbers\end , $W_2^{2+\alpha,1+\alpha/2}$\nopagenumbers\end and $W_2^{1+\alpha,1/2+\alpha/2}$\nopagenumbers\end —regularity with α∈(¾, 1), respectively. Copyright © 2001 John Wiley & Sons, Ltd.     

Existence of weak solutions to the three-dimensional problem of steady barotropic motions of mixtures of viscous compressible fluids

We consider the boundary value problem describing the steady barotropic motion of a multicomponent mixture of viscous compressible fluids in a bounded three-dimensional domain. We assume that the material derivative operator is common to all components and is defined by the average velocity of the motion, but keep separate velocities of the components in other terms. Pressure is common and depends on the total density. Beyond that we make no simplifying assumptions, including those on the structure of the viscosity matrix; i.e., we keep all terms in the equations, which naturally generalize the Navier–Stokes model of the motion of one-component media. We establish the existence of weak solutions to the boundary value problem.     

Solvability of a stationary boundary value problem for a model system of the equations of barotropic motion of a mixture of compressible viscous fluids

Under consideration is some boundary value problem for a model system of equations that describes the steady barotropic motion of a homogeneous mixture of compressible viscous fluids in a bounded three-dimensional domain. We prove the existence theorem for weak solutions of the problem, imposing no restrictions on the structure of total viscosity matrix except the standard requirements of positive definiteness.     

Local existence of solution to free boundary value problem for compressible Navier-Stokes equations

This paper is concerned with the free boundary value problem for multi-dimensional Navier-Stokes equations with density-dependent viscosity where the flow density vanishes continuously across the free boundary. Local (in time) existence of a weak solution is established; in particular, the density is positive and the solution is regular away from the free boundary.     

Local free boundary problem for viscous compressible magnetohydrodynamics

We consider the motion of viscous compressible magnetohydrodynamics fluid in a domain bounded by a free surface. In the external domain, there is electromagnetic field generated by some currents that keeps the magnetohydrodynamics flow in the bounded domain. Then on the free surface, transmission conditions for electromagnetic fields are imposed. In this paper, we prove the existence of local regular solutions by the method of successive approximations. The L₂ approach is used. This helps us to treat the transmission conditions.     

Global weak solutions to one-dimensional compressible viscous hydrodynamic equations

In this article, we are concerned with the global weak solutions to the 1D compressible viscous hydrodynamic equations with dispersion correction δ~2ρ((φ(ρ))xxφ′(ρ))x withφ(ρ) = ρα. The model consists of viscous stabilizations because of quantum Fokker-Planck operator in the Wigner equation and is supplemented with periodic boundary and initial conditions. The diffusion term εu xx in the momentum equation may be interpreted as a classical conservative friction term because of particle interactions. We extend the existence result in[1](α =1/2) to 0 α≤1. In addition, we perform the limit ε→ 0 with respect to 0 α≤1/2.     

Free boundary value problem for the one-dimensional compressible Navier-Stokes equations with density-dependent viscosity

We study the free boundary value problem for one-dimensional isentropic compressible Navier-Stokes equations with density-dependent viscosity coefficient in this paper. Under certain assumptions imposed on the initial data, we show that there exists a unique global strong solution, the interface separating the flow and vacuum state propagates along particle path and expands outwards at an algebraic time-rate, the flow density is strictly positive from blow for any finite time and decays pointwise to zero also at an algebraic time-rate as the time tends to infinity.     

Conditions for stabilization of solutions to the first boundary value problem for parabolic equations

We study the stabilization to zero of a solution to the first boundary value problem for a parabolic equation. We obtain necessary and sufficient stabilization conditions in the case of the heat equation and sufficient conditions in the case of a parabolic equation with variable coefficients. Bibliography: 14 titles.     

Strong solutions of the Navier-Stokes equations for isentropic compressible fluids

We study strong solutions of the isentropic compressible Navier-Stokes equations in a domain . We first prove the local existence of unique strong solutions provided that the initial data ρ₀ and u₀ satisfy a natural compatibility condition. The important point in this paper is that we allow the initial vacuum: the initial density may vanish in an open subset of Ω. We then prove a new uniqueness result and stability result. Our results are valid for unbounded domains as well as bounded ones.     

On the existence of global weak solutions to the Navier–Stokes equations for viscous compressible and heat conducting fluids

The purpose of this work is to investigate the problem of global in time existence of sequences of weak solutions to the Navier–Stokes equations for viscous compressible and heat conducting fluids. A class of density and temperature dependent viscosity and conductivity coefficients is considered. This result extends P.-L. Lions' work in 1993 [P.-L. Lions, Compacité des solutions des équations de Navier–Stokes compressibles isentropiques, C. R. Acad. Sci. Paris, Sér. I 317 (1993) 115–120] restricted to barotropic flows, and provides weak solutions “à la Leray” to the full compressible model that includes internal energy evolution equation with thermal conduction effects. A partial answer is therefore given to this currently widely open problem, described for instance in P.-L. Lions' book [P.-L. Lions, Mathematical Topics in Fluid Dynamics, vol. 2, Compressible Models, Oxford Science Publication, Oxford, 1998]. The proof uses the generalization to the temperature dependent case, of a new mathematical entropy equality derived by the authors in [D. Bresch, B. Desjardins, Some diffusive capillary models of Korteweg type, C. R. Acad. Sci., Paris, Section Mécanique 332 (11) (2004) 881–886]. The construction scheme of approximate solutions, using on additional regularizing effects such as capillarity, is provided in [D. Bresch, B. Desjardins, On the construction of approximate solutions for 2D viscous shallow water model and for compressible Navier–Stokes models, J. Math. Pures Appl. 86 (4) (2006) 362–368], and allows to use the stability arguments of this paper.     

Blowup of solutions for the initial boundary value problem of the 3‐dimensional compressible damped Euler equations

The blowup phenomenon of solutions is investigated for the initial boundary value problem of the 3‐dimensional compressible damped Euler equations. It is shown that if the initial functional associated with a general test function is large enough, the solutions of the damped Euler equations will blow up on finite time. Hence, a class of blowup conditions is established. Moreover, the blowup time could be estimated.     

Positive solutions for multipoint boundary value problem of fractional differential equations

In this paper, we study the existence of positive solutions for a multi-point boundary value problem of nonlinear fractional differential equations. By applying a monotone iterative method, some existence results of positive solutions are obtained. In addition, an example is included to demonstrate the main result.     

Two positive solutions of a boundary value problem for difference equations

We consider a second order vector boundary value problem for difference equations and establish criteria for the existence of at least two positive solutions by an application of a fixed point theorem in cones.     

Global solutions to the second initial boundary value problem for fully nonlinear parabolic equations

This paper is concerned with the global existence of the second initial boundary value problem for fully nonlinear parabolic equations. It is proved that when the initial data is sufficiently small, the problem admits a unique global solution. Moreover, ast goes to +∞, the solution exponentially decays to zero.     

Multiple solutions to a three-point boundary value problem for higher-order ordinary differential equations

In this paper, we provide sufficient conditions for the existence of at least three solutions to a three-point boundary value problem for higher-order ordinary differential equations. The nonlinear term f in the differential equation under consideration may depend on higher-order derivatives of arbitrary order and this is where the main novelty of this work lies. By applying the two pairs of upper and lower solutions method of Henderson and Thompson, as well as degree theory, the existence of at least three solutions of the problem is given.