arXiv subjects

Jiang Xu

Publications and source records attributed to Jiang Xu.

At least 55 records · Page 3Linked to original sources

arXiv2018

A sharp time-weighted inequality for the compressible Navier-Stokes-Poisson system in the critical $L^{p}$ framework

The compressible Navier-Stokes-Poisson system takes the form of usual Navier-Stokes equations coupled with the self-consistent Poisson equation, which is used to simulate the transport of charged particles under the electric field of electrostatic potential force. In this paper, we focus on the large time behavior of global strong solutions in the $L^{p}$ Besov spaces of critical regularity. By exploring the dissipative effect arising from Poisson potential, we posed the new regularity assumption of low frequencies and then establish a \textit{sharp} time-weighted inequality, which leads to the optimal time-decay estimates of the solution. Indeed, we see that the decay of density is faster at the half rate than that of velocity, which is a different ingredient in comparison with the situation of usual Navier-Stokes equations. Our proof mainly depends on tricky and non classical Besov product estimates with respect to various Sobolev embeddings.

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arXiv2018

Gevrey analyticity and decay for the compressible Navier-Stokes system with capillarity

We are concerned with an isothermal model of viscous and capillary compressible fluids derived by J. E. Dunn and J. Serrin (1985), which can be used as a phase transition model. Compared with the classical compressible Navier-Stokes equations, there is a smoothing effect on the density that comes from the capillary terms. First, we prove that the global solutions with critical regularity that have been constructed in [11] by the second author and B. Desjardins (2001), are Gevrey analytic. Second, we extend that result to a more general critical L p framework. As a consequence, we obtain algebraic time-decay estimates in critical Besov spaces (and even exponential decay for the high frequencies) for any derivatives of the solution. Our approach is partly inspired by the work of Bae, Biswas \& Tadmor [2] dedicated to the classical incompressible Navier-Stokes equations, and requires our establishing new bilinear estimates (of independent interest) involving the Gevrey regularity for the product or composition of functions. To the best of our knowledge, this is the first work pointing out Gevrey analyticity for a model of compressible fluids.

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arXiv2017

Global existence and optimal decay estimates of strong solutions to the compressible viscoelastic flows

This paper is dedicated to the global existence and optimal decay estimates of strong solutions to the compressible viscoelastic flows in the whole space $\mathbb{R}^n$ with any $n\geq2$. We aim at extending those works by Qian \& Zhang and Hu \& Wang to the critical $L^p$ Besov space, which is not related to the usual energy space. With aid of intrinsic properties of viscoelastic fluids as in \cite{QZ1}, we consider a more complicated hyperbolic-parabolic system than usual Navier-Stokes equations. We define "\emph{two effective velocities}", which allows us to cancel out the coupling among the density, the velocity and the deformation tensor. Consequently, the global existence of strong solutions is constructed by using elementary energy approaches only. Besides, the optimal time-decay estimates of strong solutions will be shown in the general $L^p$ critical framework, which improves those decay results due to Hu \& Wu such that initial velocity could be \textit{large highly oscillating}.

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arXiv2017

Large time behavior of strong solutions to the compressible magnetohydrodynamic system in the critical $L^{p}$ framework

In this paper, we are concerned with the compressible viscous magnetohydrodynamic (MHD) system and investigate the large time behavior of strong solutions near constant equilibrium. In the eighties, Umeda, Kawashima and Shizuta initiated the dissipative mechanism for a rather general class of symmetric hyperbolic-parabolic systems. From the point of view of dissipativity, Kawashima in his doctoral dissertation established the optimal time-decay estimates of $L^{q}$-$L^{2}(q\in [1,2)$) type for solutions to the MHD system. Here, we shall improve Kawashima's efforts and give more precise description for the large time asymptotic behavior of solutions, not only in extra Lebesgue spaces but also in a full family of Besov norms with the negative regularity index. Precisely, we show that the $L^{p}$ norm (the slightly stronger $\dot{B}^{0}_{p,1}$ one in fact) of global solutions with the critical regularity, decays like $t^{-d(\frac{1}{p}-\frac{1}{4})}$ for $t\rightarrow\infty$. In particular, taking $p=2$ and $d=3$ goes back to the classical time decay $t^{-\frac{3}{4}}$. We derive new estimates which are used to deal with the strong coupling between the magnetic field and fluid dynamics.

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arXiv2017

Optimal decay estimates in the critical $L^p$ framework for flows of compressible viscous and heat-conductive gases

The global existence issue in critical regularity spaces for the full Navier-Stokes equationssatisfied by compressible viscous and heat-conductive gases has been first addressed in \cite{D2}, then recently extended to the general $L^p$ framework in \cite{DH}.In the present work, we establish decay estimates for the global solutions constructed in \cite{DH}, under anadditional mild integrability assumption that is satisfied if the low frequencies of the initial data are in $L^{p/2}({\mathbb{R}}^d).$As a by-product we recover in dimension three the classical decay rate $t^{-\frac34}$ for $t\to+\infty$ that has been observed by A. Matsumura and T. Nishida in \cite{MN2} for solutions with high Sobolev regularity. Compared to a recent paper of us \cite{DX} dedicated to the barotropic case, not only we are able to treat the full system, but we also improve the decay rates for the high frequencies of the solution. We believe the correspondant decay exponents to be optimal.

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arXiv2016

Optimal time-decay estimates for the compressible navier-stokes equations in the critical l p framework

The global existence issue for the isentropic compressible Navier-Stokes equations in the critical regularity framework has been addressed in [7] more than fifteen years ago. However, whether (optimal) time-decay rates could be shown in general critical spaces and any dimension d $\ge$ 2 has remained an open question. Here we give a positive answer to that issue not only in the L 2 critical framework of [7] but also in the more general L p critical framework of [3, 6, 14]. More precisely, we show that under a mild additional decay assumption that is satisfied if the low frequencies of the initial data are in e.g. L p/2 (R d), the L p norm (the slightly stronger $\dot B^0_{p,1}$ norm in fact) of the critical global solutions decays like t --d(1 p -- 1 4) for t $\rightarrow$ +$\infty$, exactly as firstly observed by A. Matsumura and T. Nishida in [23] in the case p = 2 and d = 3, for solutions with high Sobolev regularity. Our method relies on refined time weighted inequalities in the Fourier space, and is likely to be effective for other hyperbolic/parabolic systems that are encountered in fluid mechanics or mathematical physics.

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arXiv2015

The frequency-localization technique and minimal decay-regularity for Euler-Maxwell equations

Dissipative hyperbolic systems of \textit{regularity-loss} have been recently received increasing attention. Usually, extra higher regularity is assumed to obtain the optimal decay estimates, in comparison with that for the global-in-time existence of solutions. In this paper, we develop a new frequency-localization time-decay property, which enables us to overcome the technical difficulty and improve the minimal decay-regularity for dissipative systems. As an application, it is shown that the optimal decay rate of $L^1(\mathbb{R}^3)$-$L^2(\mathbb{R}^3)$ is available for Euler-Maxwell equations with the critical regularity $s_{c}=5/2$, that is, the extra higher regularity is not needed.

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arXiv2015

Global existence and minimal decay regularity for the Timoshenko system: The case of non-equal wave speeds

As a continued work of [18], we are concerned with the Timoshenko system in the case of non-equal wave speeds, which admits the dissipative structure of \textit{regularity-loss}. Firstly, with the modification of a priori estimates in [18], we construct global solutions to the Timoshenko system pertaining to data in the Besov space with the regularity $s=3/2$. Owing to the weaker dissipative mechanism, extra higher regularity than that for the global-in-time existence is usually imposed to obtain the optimal decay rates of classical solutions, so it is almost impossible to obtain the optimal decay rates in the critical space. To overcome the outstanding difficulty, we develop a new frequency-localization time-decay inequality, which captures the information related to the integrability at the high-frequency part. Furthermore, by the energy approach in terms of high-frequency and low-frequency decomposition, we show the optimal decay rate for Timoshenko system in critical Besov spaces, which improves previous works greatly.

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arXiv2014

$L^p$-$L^{q}$-$L^{r}$ estimates and minimal decay regularity for compressible Euler-Maxwell equations

Due to the dissipative structure of \textit{regularity-loss}, extra higher regularity than that for the global-in-time existence is usually imposed to obtain the optimal decay rates of classical solutions to dissipative systems. The aim of this paper is to seek the lowest regularity index for the optimal decay rate of $L^{1}(\mathbb{R}^n)$-$L^2(\mathbb{R}^n)$. Consequently, a notion of minimal decay regularity for dissipative systems of regularity-loss is firstly proposed. To do this, we develop a new time-decay estimate of $L^p(\mathbb{R}^n)$-$L^{q}(\mathbb{R}^n)$-$L^{r}(\mathbb{R}^n)$ type by using the low frequency and high-frequency analysis in Fourier spaces. As an application, for compressible Euler-Maxwell equations with the weaker dissipative mechanism, it is shown that the minimal decay regularity coincides with the critical regularity for global classical solutions. Moreover, the recent decay property for symmetric hyperbolic systems with non-symmetric dissipation is also extended to be the $L^p$-version.

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arXiv2014

Frequency-localization Duhamel principle and its application to the optimal decay of dissipative systems

Very recently, a new decay framework has been given by [51] for linearized dissipative hyperbolic systems satisfying the Kawashima-Shizuta condition on the framework of Besov spaces, which allows to pay less attention on the traditional spectral analysis. However, owing to interpolation techniques, the analysis remains valid only for nonlinear systems in higher dimensions $(n\geq3)$ and the corresponding case of low dimensions was left open, which provides the main motivation of this work. Firstly, we develop new time-decay properties on the frequency-localization Duhamel principle. Furthermore, it is shown that the classical solution and its derivatives of fractional order decay at the optimal algebraic rate in dimension 1, by time-weighted energy approaches in terms of low-frequency and high-frequency decompositions. Finally, as applications, decay results for several concrete systems subjected to the same dissipative structure as general hyperbolic systems, for instance, damped compressible Euler equations, thermoelasticity with second sound and Timoshenko systems with equal wave speeds, are also obtained.

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arXiv2014

Global existence and optimal decay rates for the Timoshenko system: the case of equal wave speeds

This work first gives the global existence and optimal decay rates of solutions to the classical Timoshenko system on the framework of Besov spaces. Due to the \textit{non-symmetric} dissipation, the general theory for dissipative hyperbolic systems ([30]) can not be applied to the Timoshenko system directly. In the case of equal wave speeds, we construct global solutions to the Cauchy problem pertaining to data in the spatially Besov spaces. Furthermore, the dissipative structure enables us to give a new decay framework which pays less attention on the traditional spectral analysis. Consequently, the optimal decay estimates of solution and its derivatives of fractional order are shown by time-weighted energy approaches in terms of low-frequency and high-frequency decompositions. As a by-product, the usual decay estimate of $L^{1}(\mathbb{R})$-$L^{2}(\mathbb{R})$ type is also shown.

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arXiv2014

The optimal decay estimates for the Euler-Poisson two-fluid system

This work is devoted to the optimal decay problem for the Euler-Poisson two-fluid system, which is a classical hydrodynamic model arising in semiconductor sciences. By exploring the influence of the electronic field on the dissipative structure, it is first revealed that the \textit{irrotationality} plays a key role such that the two-fluid system has the same dissipative structure as generally hyperbolic systems satisfying the Shizuta-Kawashima condition. The fact inspires us to give a new decay framework which pays less attention on the traditional spectral analysis. Furthermore, various decay estimates of solution and its derivatives of fractional order on the framework of Besov spaces are obtained by time-weighted energy approaches in terms of low-frequency and high-frequency decompositions. As direct consequences, the optimal decay rates of $L^{p}(\mathbb{R}^{3})$-$L^{2}(\mathbb{R}^{3})(1\leq p<2)$ type for the Euler-Poisson two-fluid system are also shown.

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arXiv2014

The optimal decay estimates on the framework of Besov spaces for generally dissipative systems

We give a new decay framework for general dissipative hyperbolic system and hyperbolic-parabolic composite system, which allow us to pay less attention on the traditional spectral analysis in comparison with previous efforts. New ingredients lie in the high-frequency and low-frequency decomposition of a pseudo-differential operator and an interpolation inequality related to homogeneous Besov spaces of negative order. Furthermore, we develop the Littlewood-Paley pointwise energy estimates and new time-weighted energy functionals to establish the optimal decay estimates on the framework of spatially critical Besov spaces for degenerately dissipative hyperbolic system of balance laws. Based on the $L^{p}(\mathbb{R}^{n})$ embedding and improved Gagliardo-Nirenberg inequality, the optimal $L^{p}(\mathbb{R}^{n})$-$L^{2}(\mathbb{R}^{n})(1\leq p<2)$ decay rates and $L^{p}(\mathbb{R}^{n})$-$L^{q}(\mathbb{R}^{n})(1\leq p<2\leq q\leq\infty)$ decay rates are further shown. Finally, as a direct application, the optimal decay rates for 3D damped compressible Euler equations are also obtained.

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arXiv2013

Global well-posedness in spatially critical Besov space for the Boltzmann equation

The unique global strong solution in the Chemin-Lerner type space to the Cauchy problem on the Boltzmann equation for hard potentials is constructed in perturbation framework. Such solution space is of critical regularity with respect to spatial variable, and it can capture the intrinsic property of the Botlzmann equation. For the proof of global well-posedness, we develop some new estimates on the nonlinear collision term through the Littlewood-Paley theory.

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arXiv2013

Commutator estimates in Besov-Morrey spaces with applications to the well-posedness of the Euler equations and ideal MHD system

We develop commutator estimates in the framework of Besov-Morrey spaces, which are modeled on Besov spaces and the underlying norm is of Morrey space rather than the usual $L^{p}$ space. As direct applications of commutator estimates, we establish the local well-posedness and blow-up criterion of solutions in Besov-Morrey spaces for the incompressible Euler equations and ideal MHD system. Main analysis tools are the Littlewood-Paley decomposition and Bony's para-product formula.

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arXiv2013

Relaxation limit in larger Besov spaces for compressible Euler equations

The work is devoted to the relaxation limit in larger Besov spaces for compressible Euler equations, which contains previous results in Sobolev spaces and Besov spaces with critical regularity. Such an extension depends on a revision of commutator estimates and an elementary fact which indicates the connection between homogeneous and inhomogeneous Chemin-Lerner spaces.

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arXiv2012

Global well-posedness in critical Besov spaces for two-fluid Euler-Maxwell equations

In this paper, we study the well-posedness in critical Besov spaces for two-fluid Euler-Maxwell equations, which is different from the one fluid case. We need to deal with the difficulties mainly caused by the nonlinear coupling and cancelation between two carriers. Precisely, we first obtain the local existence and blow-up criterion of classical solutions to the Cauchy problem and periodic problem pertaining to data in Besov spaces with critical regularity. Furthermore, we construct the global existence of classical solutions with aid of a different energy estimate (in comparison with the one-fluid case) provided the initial data is small under certain norms. Finally, we establish the large-time asymptotic behavior of global solutions near equilibrium in Besov spaces with relatively lower regularity.

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arXiv2012

Zero-electron-mass limit of Euler-Poisson equations

This paper is concerned with multidimensional Euler-Poisson equations for plasmas. The equations take the form of Euler equations for the conservation laws of the mass density and current density for charge-carriers (electrons and ions), coupled to a Poisson equation for the electrostatic potential. We study the limit to zero of some physical parameters which arise in the scaled Euler-Poisson equations, more precisely, which is the limit of vanishing ratio of the electron mass to the ion mass. When the initial data are small in critical Besov spaces, by virtue of the ``Shizuta-Kawashima" skew-symmetry condition, we establish the uniform global existence and uniqueness of classical solutions. Then we develop new frequency-localization Strichartz-type estimates for the equation of acoustics (a modified wave equation) with the aid of the detailed analysis of the semigroup formulation generated by this modified wave operator. Finally, it is shown that the uniform classical solutions converge towards that of the incompressible Euler equations (for \textit{ill-prepared} initial data) in a refined way as the scaled electron-mass tends to zero.

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