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Xiaoping Zhai

Publications and source records attributed to Xiaoping Zhai.

At least 37 records · Page 2Linked to original sources
arXiv2021

Global well-posedness and inviscid limits of the generalized Oldroyd type models

We obtain the global small solutions to the generalized Oldroyd-B model without damping on the stress tensor in $\mathbb{R}^n$. Our result give positive answers partially to the question proposed by Elgindi and Liu (Remark 2 in Elgindi and Liu [J Differ Equ 259:1958--1966, 2015)]. The proof relies heavily on the trick of transferring dissipation from $u$ to $τ$, and a new commutator estimate which may be of interest for future works. Moreover, we prove a global result of inviscid limit of two dimensional Oldroyd type models in the Sobolev spaces. The convergence rate is also obtained simultaneously.

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arXiv2021

Global small solutions to the inviscid Hall-MHD system

The local existence of smooth solutions to the inviscid Hall-MHD system has been obtained since Chae, Degond and Liu [Ann. Inst. H. Poincaré Anal. Non Linéaire, {31} (2014), 555--565]. However, as we known, how to construct the global small solutions to the inviscid Hall-MHD system is still an open problem. In the present paper, we give a positive answer in $ \mathbb{T}^3$ when the initial magnetic field is close to a background magnetic field satisfying the Diophantine condition.

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arXiv2021

Linear stability analysis of the Couette flow for the two dimensional non-isentropic compressible Euler equations

This note is devoted to the linear stability of the Couette flow for the non-isentropic compressible Euler equations in a domain $\mathbb{T}\times \mathbb{R}$. Exploiting the several conservation laws originated from the special structure of the linear system, we obtain a Lyapunov type instability for the density, the temperature, the compressible part of the velocity field, and also obtain an inviscid damping for the incompressible part of the velocity field.

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arXiv2021

Global wellposedness and large time behavior of solutions to the $n$-dimensional compressible Oldroyd-B model

The purpose of this work is to study the global wellposedness and large time behavior results of strong solutions for the compressible Oldroyd-B model derived by Barrett, Lu, Süli (Commun. Math. Sci., 15, 1265--1323, 2017). Exploiting the Harmonic analysis tools (especially Littlewood-Paley theory), we first study the global well-posedness of the model with small initial data in spaces with low regularity. Then, under a suitable condition involving only the low frequency of the initial data, we also obtain the optimal decay rates of the solutions. Compared with the result by Wang and Wen (Math. Models Methods Appl. Sci., 30, 139--179, 2020), the polymer number density is allowed to vanish and the stress tensor isnear zero equilibrium.

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arXiv2020

Global solutions to the $n$-dimensional incompressible Oldroyd-B model without damping mechanism

The present work is dedicated to the global solutions to the incompressible Oldroyd-B model without damping on the stress tensor in $\mathbb{R}^n(n=2,3)$. This result allows to construct global solutions for a class of highly oscillating initial velocity. The proof uses the special structure of the system. Moreover, our theorem extends the previous result by Zhu [19] and covers the recent result by Chen and Hao [4].

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arXiv2020

Global wellposedness to the $n$-dimensional compressible Oldroyd-B model without damping mechanism

The Cauchy problem of the compressible Oldroyd-B model without damping mechanism in R^n$ with $n\ge2$ is considered. The lack of dissipation in density and stress tensor in the model is compensated by exploiting an intrinsic structure and introducing new quantities between density, velocity and stress tensor. Therefore, global solutions to the system with small initial data in critical Besov spaces are obtained. As a byproduct, optimal time decay rates of the solutions are derived by using an energy estimation argument. The results remain valid for the compressible viscoelastic system without the `div-curl structure assumption and thus improve those given by Hu and Wang [ J. Differential Equations, {\bf 250}, 1200--1231, 2011] and Qian and Zhang [Arch. Ration. Mech. Anal., {\bf 198}, 835--868, 2010].

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arXiv2019

Long-time behavior for three dimensional compressible viscous and heat-conductive gases

We study the large-time behavior of solutions to the compressible Navier-Stokes equations for a viscous and heat-conductive gases in $\mathbb{R}^3$. More precisely, under a suitable additional condition involving only the low frequencies of the initial data, we exhibit the optimal time decay rates for the constructed global solutions. The proof relies on some new energy arguments developed by Xin and Xu [39] for the compressible Navier-Stokes equations.

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arXiv2019

Optimal decay for the $n$-dimensional incompressible Oldroyd-B model without damping mechanism

By a new energy approach involved in the high frequencies and low frequencies decomposition in the Besov spaces, we obtain the optimal decay for the incompressible Oldroyd-B model without damping mechanism in $\mathbb{R}^n$ ($n\ge 2$). More precisely, let $(u,τ)$ be the global small solutions constructed in [18], we prove for any $(u_0,τ_0)\in{\dot{B}_{2,1}^{-s}}(\mathbb{R}^n)$ that \begin{eqnarray*} \big\|Λ^α(u,Λ^{-1}\mathbb{P}\mathrm{div}τ)\big\|_{L^q} \le C (1+t)^{-\frac n4-\frac {(α+s)q-n}{2q}}, \quadΛ\stackrel{\mathrm{def}}{=}\sqrt{-Δ}, \end{eqnarray*} with $\frac n2-1<s<\frac np, $ $2\leq p \leq \min(4,{2n}/({n-2})),\ p\not=4\ \hbox{ if }\ n=2,$ and $p\leq q\leq\infty$, $\frac nq-\frac np-s<α\leq\frac nq-1$. The proof relies heavily on the special dissipative structure of the equations and some commutator estimates and various interpolations between Besov type spaces. The method also works for other parabolic-hyperbolic systems in which the Fourier splitting technique is invalid.

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arXiv2019

Global large solutions and incompressible limit for the compressible Navier-Stokes equations

The present paper is dedicated to the global large solutions and incompressible limit for the compressible Navier-Stokes system in $\mathbb{R}^d$ with $d\ge 2$. We aim at extending the work by Danchin and Mucha (Adv. Math., 320, 904--925, 2017) in $L^2$ structure to that in a critical $L^p$ framework. The result implies the existence of global large solutions initially from large highly oscillating velocity fields.

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arXiv2019

Global well-posedness for the Phan-Thein-Tanner model in critical Besov spaces without damping

In this paper, we mainly investigate the Cauchy problem for the Phan-Thein-Tanner (PTT) model. The PPT model can be viewed as a Navier-Stokes equations couple with a nonlinear transport system. This model is derived from network theory for the polymeric fluid. We study about the global well posedness of the PTT model in critical Besov spaces. When the initial data is a small perturbation over around the equilibrium, we prove that the strong solution in critical Besov spaces exists globally.

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arXiv2016

Global well-posedness for the 3D incompressible inhomogeneous Navier-Stokes equations and MHD equations

The present paper is dedicated to the global well-posedness for the 3D inhomogeneous incompressible Navier-Stokes equations, in critical Besov spaces without smallness assumption on the variation of the density. We aim at extending the work by Abidi, Gui and Zhang (Arch. Ration. Mech. Anal. 204 (1):189--230, 2012, and J. Math. Pures Appl. 100 (1):166--203, 2013) to a more lower regularity index about the initial velocity. The key to that improvement is a new a priori estimate for an elliptic equation with nonconstant coefficients in Besov spaces which have the same degree as $L^2$ in $\mathbb{R}^3$. Finally, we also generalize our well-posedness result to the inhomogeneous incompressible MHD equations.

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arXiv2016

The Cauchy problem for higher-order modified Camassa-Holm equations on the circle

In this paper, we investigate the Cauchy problem for the shallow water type equation \begin{eqnarray*} u_{t}+\partial_{x}^{2j+1}u + \frac{1}{2}\partial_{x}(u^{2})+ \partial_{x}(1-\partial_{x}^{2})^{-1}\left[u^{2}+\frac{1}{2}u_{x}^{2}\right]=0 \end{eqnarray*} with low regularity data in the periodic settings. Himonas and Misiolek (Communications in Partial Differential Equations, 23(1998), 123-139.) have proved that the problem is locally well-posed for small initial data in H^{s}(\mathbf{T}) with s\geq-\frac{j}{2}+1,j\in N^{+} with the aid of the standard Fourier restriction norm method. To the best of our knowledge, there is no result of well-posedness about the problem when s<-\frac{j}{2}+1. In this paper, firstly, we prove that the bilinear estimate related to the nonlinear term of the equation in standard Bourgain space is invalid with s<-\frac{j}{2}+1. Then we prove that the Cauchy problem for the periodic shallow water-type equation is locally well-posed in H^{s}(\mathbf{T}) with -j+\frac{3}{2}< s<-\frac{j}{2}+1,j\geq2 for arbitrary initial data. The novelty is that we introduce some new function spaces and give a useful relationship among new spaces.

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arXiv2016

The Cauchy problem for the shallow water typ equations in low regularity spaces on the circle

In this paper, we investigate the Cauchy problem for the shallow water type equation \[ u_{t}+\partial_{x}^{3}u + \frac{1}{2}\partial_{x}(u^{2})+\partial_{x} (1-\partial_{x}^{2})^{-1}\left[u^{2}+\frac{1}{2}u_{x}^{2}\right]=0,x\in {\mathbf T}=\R/2π λ\] with low regularity data in the periodic settings and $λ\geq1$. We prove that the bilinear estimate in $X_{s,b}$ with $s<\frac{1}{2}$ is invalid. We also prove that the problem is locally well-posed in $H^{s}(\mathbf{T})$ with $\frac{1}{6}<s<\frac{1}{2}$ for small initial data. The result of this paper improves the result of case $j=1$ of Himonas and Misiolek (Communications in Partial Differential Equations, 23(1998), 123-139.). The new ingredients are some new function spaces and some new Strichartz estimates.

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arXiv2015

On the Well-posedness of 2-D Incompressible Navier-Stokes Equations with Variable Viscosity in Critical Spaces

In this paper, we first prove the local well-posedness of the 2-D incompressible Navier-Stokes equations with variable viscosity in critical Besov spaces with negative regularity indices, without smallness assumption on the variation of the density. The key is to prove for $p\in(1,4)$ and $a\in\dot{B}_{p,1}^{\frac2p}(\mathbb{R}^2)$ that the solution mapping $\mathcal{H}_a:F\mapsto\nablaΠ$ to the 2-D elliptic equation $\mathrm{div}\big((1+a)\nablaΠ\big)=\mathrm{div} F$ is bounded on $\dot{B}_{p,1}^{\frac2p-1}(\mathbb{R}^2)$. More precisely, we prove that $$\|\nablaΠ\|_{\dot{B}_{p,1}^{\frac2p-1}}\leq C\big(1+\|a\|_{\dot{B}_{p,1}^{\frac2p}}\big)^2\|F\|_{\dot{B}_{p,1}^{\frac2p-1}}.$$ The proof of the uniqueness of solution to (1.2) relies on a Lagrangian approach [15]-[17]. When the viscosity coefficient $μ(ρ)$ is a positive constant, we prove that (1.2) is globally well-posed.

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