On the uniqueness for the 2D MHD equations without magnetic diffusion

Non-uniqueness of entropy-conserving solutions to the ideal compressible MHD equations

In this note we consider the ideal compressible magneto-hydrodynamics (MHD) equations in a special two dimensional setting. We show that there exist particular initial data for which one obtains infinitely many entropy-conserving weak solutions by using the convex integration technique. Our result is also true for the isentropic case.

受迫MHD方程Leray弱解的非唯一性

Non-uniqueness of Leray weak solutions of the forced MHD equations

本研究针对受迫MHD方程，通过构造不稳定背景解及对应不稳定流形上的轨道，证明了其Leray弱解的非唯一性，且解处于已知适定性理论边界。

Weak-strong uniqueness in weighted $L^2$ spaces and weak suitable solutions in local Morrey spaces for the MHD equations

We consider here the magneto-hydrodynamics (MHD) equations on the whole space. For the 3D case, in the setting of the weighted $L^2$ spaces we obtain a weak-strong uniqueness criterion provided that the velocity field and the magnetic field belong to a fairly general multipliers space. On the other hand, we study the local and global existence of weak suitable solutions for intermittent initial data, which is characterized through a local Morrey space. This large initial data space was also exhibit in a contemporary work [4] in the context of 3D Navier-Stokes equations. Finally, we make a disc…

An elementary proof of the global existence and uniqueness theorem to 2-D incompressible non-resistive MHD system

In this paper, we provide a much simplified proof of the main result in [Lin, Xu, Zhang, arXiv:1302.5877] concerning the global existence and uniqueness of smooth solutions to the Cauchy problem for a 2D incompressible viscous and non-resistive MHD system under the assumption that the initial data are close to some equilibrium states. Beside the classical energy method, the interpolating inequalities and the algebraic structure of the equations coming from the incompressibility of the fluid are crucial in our arguments. We combine the energy estimates with the $L^\infty$ estimates for time sli…

平面上 3D Hall-MHD 方程弱解的非唯一性

Non-uniqueness of weak solutions to the 3D Hall-MHD equations on the plane

通过凸积分格式和新间歇流构造，证明了平面上 3D Hall-MHD 方程具有非平凡磁场的弱解非唯一性，并发现其不守恒磁螺旋性，且理想解为强零粘与零电阻极限。

次耗散可压缩三维磁流体力学方程组的非唯一性

Non-uniqueness for the hypo-dissipative compressible 3D magnetohydrodynamic equations

针对一般压力律下的可压缩三维磁流体力学方程组，证明了在次粘性和次电阻率条件下弱解的非唯一性，并建立了理想MHD光滑解作为次耗散MHD弱解粘性消失极限的结论。

Non-uniqueness of weak solutions to 3D magnetohydrodynamic equations

We prove the non-uniqueness of weak solutions to 3D magnetohydrodynamic (MHD for short) equations. The constructed weak solutions do not conserve the magnetic helicity and can be close to any given smooth, divergence-free and mean-free velocity and magnetic fields. Furthermore, we prove that the weak solutions constructed by Beekie-Buckmaster-Vicol [2] for the ideal MHD can be obtained as a strong vanishing viscosity and resistivity limit of a sequence of weak solutions to MHD equations. This shows that, in contrast to the weak ideal limits, Taylor's conjecture does not hold along the vanishin…

MHD方程中大$ L^3 $初值弱解的全局存在性与唯一性

Global existence and uniqueness of weak solutions for the MHD equations with large $L^3$-initial values

本文通过勒雷近似技术和扰动理论，研究了大$ L^3 $初值下MHD方程弱解的全局存在性和唯一性，同时提供了不可压缩纳维-斯托克斯系统弱$ L^3 $解理论的简洁证明。

MHD光滑解的瞬时爆破与不唯一性

Instantaneous blowup and non-uniqueness of smooth solutions of MHD

通过逆能量级联机制和凸积分方法，构造了不可压缩磁流体动力学（MHD）系统的一族解，其L∞范数以临界速率瞬时爆破，且解在爆破时间之前保持光滑。

随机理想二进磁流体动力学模型的唯一性

Uniqueness for a stochastic ideal dyadic MHD model

研究无粘性无电阻磁流体动力学随机二进模型，针对特定随机强迫证明弱唯一性，但解耗散形式上守恒的能量。

关于具有可控总能量和交叉螺旋度的MHD系统弱解

On the weak solutions for the MHD systems with controllable total energy and cross helicity

本文通过构造六种箱式流的凸积分扰动，证明了粘性电阻MHD系统在给定时间区间内总能量和交叉螺旋度可控时的弱解非唯一性，将理想MHD的结果推广至耗散情形。

Global regularity for the 2D MHD equations with mixed partial dissipation and magnetic diffusion

Whether or not classical solutions of the 2D incompressible MHD equations without full dissipation and magnetic diffusion can develop finite-time singularities is a difficult issue. A major result of this paper establishes the global regularity of classical solutions for the MHD equations with mixed partial dissipation and magnetic diffusion. In addition, the global existence, conditional regularity and uniqueness of a weak solution is obtained for the 2D MHD equations with only magnetic diffusion.

Sharp non-uniqueness of weak solutions to 3D magnetohydrodynamic equations

We prove the non-uniqueness of weak solutions to 3D hyper viscous and resistive MHD in the class $L^γ_tW^{s,p}_x$, where the exponents $(s,γ,p)$ lie in two supercritical regimes. The result reveals that the scaling-invariant Ladyženskaja-Prodi-Serrin (LPS) condition is the right criterion to detect non-uniqueness, even in the highly viscous and resistive regime beyond the Lions exponent. In particular, for the classical viscous and resistive MHD, the non-uniqueness is sharp near the endpoint $(0,2,\infty)$ of the LPS condition. Moreover, the constructed weak solutions admit the partial regular…

Existence and uniqueness of low-energy weak solutions to the compressible 3D magnetohydrodynamics equations

We prove the existence and uniqueness of weak solutions of the three dimensional compressible magnetohydrodynamics (MHD) equations. We first obtain the existence of weak solutions with small $L^2$-norm which may display codimension-one discontinuities in density, pressure, magnetic field and velocity gradient. The weak solutions we consider here exhibit just enough regularity and structure which allow us to develop uniqueness and continuous dependence theory for the compressible MHD equations. Our results generalise and extend those for the intermediate weak solutions of compressible Navier-St…

The continuous dependence for the Hal-MHD equations with fractional magnetic diffusion

In this paper we show that the solutions to the incompressible Hall-MHD system with fractional magnetic diffusion depend continuously on the initial data in $H^s(\mathbb{R}^d)$, $s>1+\frac{d}{2}$.

The Stochastic Tamed MHD Equations -- Existence, Uniqueness and Invariant Measures

We study the tamed magnetohydrodynamics equations, introduced recently in a paper by the author, perturbed by multiplicative Wiener noise of transport type on the whole space $\mathbb{R}^{3}$ and on the torus $\mathbb{T}^{3}$. In a first step, existence of a unique strong solution are established by constructing a weak solution, proving that pathwise uniqueness holds and using the Yamada-Watanabe theorem. We then study the associated Markov semigroup and prove that it has the Feller property. Finally, existence of an invariant measure of the equation is shown for the case of the torus.

具有垂直耗散和磁扩散的轴对称MHD方程的低正则性全局适定性

Low regularity global well-posedness of axisymmetric MHD equations with vertical dissipation and magnetic diffusion

本文研究仅含垂直耗散和磁扩散的三维轴对称MHD方程，通过高阶能量估计和实插值方法，证明了Lorentz空间中初始数据的唯一低正则性全局解的存在性。

Global classical solutions of 2D MHD system with only magnetic diffusion on periodic domain

This paper studies the global existence of classical solutions to the two-dimensional incompressible magneto-hydrodynamical (MHD) system with only magnetic diffusion on the periodic domain. The approach is based on a time-weighted energy estimate, under the assumptions that the initial magnetic field is close enough to an equilibrium state and the initial data have reflection symmetry.

Global Regularity of 2D Generalized MHD Equations with Magnetic Diffusion

This paper is concerned with the global regularity of the 2D (two-dimensional) generalized magnetohydrodynamic equations with only magnetic diffusion $Λ^{2β} b$. It is proved that when $β>1 $ there exists a unique global regular solution for this equations. The obtained result improves the previous known one which requires that $β>\frac32$.

Sharp and strong non-uniqueness for the magneto-hydrodynamic equations

In this paper, we prove a sharp and strong non-uniqueness for a class of weak solutions to the three-dimensional magneto-hydrodynamic (MHD) system. More precisely, we show that any weak solution $(v,b)\in L^p_tL^{\infty}_x$ is non-unique in $L^p_tL^{\infty}_x$ with $1\le p<2$, which reveals the strong non-uniqueness, and the sharpness in terms of the classical Ladyzhenskaya-Prodi-Serrin criteria at endpoint $(2, \infty)$. Moreover, for any $1\le p<2$ and $ε>0$, we construct non-Leray-Hopf weak solutions in $L^p_tL^{\infty}_x\cap L^1_tC^{1-ε}$. The results of Navier-Stokes equations in \cite{1C…

Remark on the global regularity of 2D MHD equations with almost Laplacian magnetic diffusion

Whether or not the classical solutions of the two-dimensional (2D) incompressible magnetohydrodynamics (MHD) equations with only Laplacian magnetic diffusion (without velocity dissipation) are globally well-posed is a difficult problem and remains completely open. In this paper, we establish the global regularity of solutions to the 2D incompressible MHD equations with almost Laplacian magnetic diffusion in the whole space. This result can be regarded as a further improvement and generalization of the previous works. Consequently, our result is more closer to the resolution of the global regul…

具有部分磁扩散的三维可压缩磁流体力学方程的全局解

Global solutions to 3D compressible MHD equations with partial magnetic diffusion

本文研究三维可压缩粘性MHD方程在仅具有水平磁扩散时的柯西问题，利用各向异性Sobolev不等式和精细估计，在小初值条件下证明了全局解的存在性。

Global solutions of 3D incompressible MHD system with mixed partial dissipation and magnetic diffusion near an equilibrium

This paper focuses on the 3D incompressible magnetohydrodynamic (MHD) equations with mixed partial dissipation and magnetic diffusion. Our main result assesses the global stability of perturbations near the steady solution given by a background magnetic field. The stability problem on the MHD equations with partial or no dissipation has attracted considerable interests recently and there are substantial developments. The new stability result presented here is among the very few stability conclusions currently available for ideal or partially dissipated MHD equations. As a special consequence o…

The Tamed MHD Equations

We study a regularised version of the magnetohydrodynamics (MHD) equations, the tamed MHD (TMHD) equations. They are a model for the flow of electrically conducting fluids through porous media. We prove existence and uniqueness of TMHD on the whole space $\mathbb{R}^{3}$, that smooth data give rise to smooth solutions, and show that solutions to TMHD converge to a suitable weak solution of the MHD equations as the taming parameter $N$ tends to infinity. Furthermore, we adapt a regularity result for the Navier-Stokes equations to the MHD case.

仅有磁扩散的二维不可压缩MHD方程的稳定性

Stability for the 2D incompressible MHD equations with only magnetic diffusion

本文针对周期域上仅有磁扩散的二维不可压缩MHD方程，证明了背景磁场附近扰动的全局稳定性，并得出解的显式长时间衰减率，揭示了磁场的稳定作用。

On the local well-posedness and a Prodi-Serrin type regularity criterion of the three-dimensional MHD-Boussinesq system without thermal diffusion

We prove a Prodi-Serrin-type global regularity condition for the three-dimensional Magnetohydrodynamic-Boussinesq system (3D MHD-Boussinesq) without thermal diffusion, in terms of only two velocity and two magnetic components. This is the first Prodi-Serrin-type criterion for a hydrodynamic system which is not fully dissipative, and indicates that such an approach may be successful on other systems. In addition, we provide a constructive proof of the local well-posedness of solutions to the fully dissipative 3D MHD-Boussinesq system, and also the fully inviscid, irresistive, non-diffusive MHD-…

Global regularity for the 2D MHD equations with horizontal dissipation and horizontal magnetic diffusion

This paper establishes the global regularity of classical solution to the 2D MHD system with only horizontal dissipation and horizontal magnetic diffusion in a strip domain $\mathbb{T}\times\mathbb{R}$ when the initial data is suitable small. To prove this, we combine the Littlewood-Paley decomposition with anisotropic inequalities to establish a crucial commutator estimate. We also analysis the asymptotic behavior of the solution. In addition, the global existence and uniqueness of classical solution is obtained for the 2D simplified tropical climate model with only horizontal dissipations.

Local well-posedness for the Hall-MHD equations with fractional magnetic diffusion

The Hall-magnetohydrodynamics (Hall-MHD) equations, rigorously derived from kinetic models, are useful in describing many physical phenomena in geophysics and astrophysics. This paper studies the local well-posedness of classical solutions to the Hall-MHD equations with the magnetic diffusion given by a fractional Laplacian operator, $(-Δ)^α$. Due to the presence of the Hall term in the Hall-MHD equations, standard energy estimates appear to indicate that we need $α\ge 1$ in order to obtain the local well-posedness. This paper breaks the barrier and shows that the fractional Hall-MHD equations…

Global weak solutions to the one-dimensional compressible heat-conductive MHD equations without resistivity

We investigate the initial-boundary value problem for one-dimensional compressible, heat-conductive, non-resistive MHD equations of viscous, ideal polytropic fluids in the Lagrangian coordinates. The existence and Lipschitz continuous dependence on the initial data of global weak solutions are established. Uniqueness of weak solutions follows as a direct consequence of stability.

Non-uniform decay of MHD equations with and without magnetic diffusion

We consider the long time behavior of solutions to the magnetohydrodynamics equations in two and three spatial dimensions. It is shown that in the absence of magnetic diffusion, if strong bounded solutions were to exist their energy cannot present any asymptotic oscillatory behavior, the diffusivity of the velocity is enough to prevent such oscillations. When magnetic diffusion is present and the data is only in L^2, it is shown that the solutions decay to zero without a rate, and this nonuniform decay is optimal.

Global classical solutions of 3D viscous MHD system without magnetic diffusion on periodic boxes

In this paper, we study the global existence of classical solutions to the three dimensional incompressible viscous magneto-hydrodynamical system without magnetic diffusion on periodic boxes, i.e., with periodic boundary conditions. We work in Eulerian coordinate and employ a time-weighted energy estimate to prove the global existence result, under the assumptions that the initial magnetic field is close enough to an equilibrium state and the initial data have some symmetries.

无磁扩散的 MHD 方程的轴对称自相似解

Axisymmetric self-similar solutions to the MHD equations without magnetic diffusion

本文研究了无磁扩散的定常 MHD 方程的轴对称自相似解，证明了在全空间（除原点外）解的特定形式以及半空间中在特定边界条件下解的平凡性。

MHD方程中仅磁扩散的非均匀连续性

Non-uniform Continuity for the MHD equations with only Magnetic Diffusion

本文研究了仅磁扩散的MHD方程在Sobolev空间中数据到解映射的非均匀连续性，并揭示强磁场背景对稳定性的影响。

二维磁流体动力学方程弱解的尖锐非唯一性

Sharp non-uniqueness of weak solutions to 2D magnetohydrodynamic equations

本文证明二维粘性电阻磁流体动力学（MHD）方程在$L^2_t L^p(\mathbb{R}^2) \cap L^1_t W^{1,p}(\mathbb{R}^2)$中弱解非唯一，其中$1\le p<\infty$，展示了Ladyzhenskaya-Prodi-Serrin条件在端点$(2,\infty)$的尖锐性，且解位于Beale-Kato-Majda准则的边界上。

Large time behavior of the solutions to 3D incompressible MHD system with horizontal dissipation or horizontal magnetic diffusion

In this paper, we consider the asymptotic behavior of global solutions to 3D anisotropic incompressible MHD systems. For the 3D MHD system with horizontal dissipation and full magnetic diffusion, it is shown that $\uh(t)$ decays at the rate of $O(t^{-(1-\f{1}{p})})$, $u_3(t)$ decays at the rate of $O(t^{-\f{3}{2}(1-\f{1}{p})})$ and $B(t)$ decays at the rate of $O(t^{-\f{3}{2}(1-\f{1}{p})-\f{1}{2}})$. Furthermore, we give the asymptotic expansion of solutions. We prove that the leading term of $\uh(t)$ is a combination of linear solution and two integrals from nonlinear coupling effects, while …

Initial-boundary value problem to 2D Boussinesq equations for MHD convection with stratification effects

This paper is concerned with the initial-boundary value problem to 2D magnetohydrodynamics-Boussinesq system with the temperature-dependent viscosity, thermal diffusivity and electrical conductivity. First, we establish the global weak solutions under the minimal initial assumption. Then by imposing higher regularity assumption on the initial data, we obtain the global strong solution with uniqueness. Moreover, the exponential decay estimate of the solution is obtained.

高维理想磁流体方程非唯一性的建立：通过微分包含

Nonuniqueness for high-dimensional ideal MHD equations via differential inclusion

本文通过微分包含框架，证明了高维理想磁流体方程存在无限多个弱解，揭示了解的非唯一性及能量守恒的失效。

Global Classical Solutions to the 2D Compressible MHD Equations with Large Data and Vacuum

In this paper, we study the global well-posedness of classical solutions to the 2D compressible MHD equations with large initial data and vacuum. With the assumption $μ=const.$ and $λ=ρ^β,~β>1$ (Vaǐgant-Kazhikhov Model) for the viscosity coefficients, the global existence and uniqueness of classical solutions to the initial value problem is established on the torus $\mathbb{T}^2$ and the whole space $\mathbb{R}^2$ (with vacuum or non-vacuum far fields). These results generalize the previous ones for the Vaǐgant-Kazhikhov model of compressible Navier-Stokes.

Sobolev空间中MHD边界层方程的全局适定性

Global well-posedness of the MHD boundary layer equations in the Sobolev Space

本文研究二维MHD边界层方程，针对切向背景磁场的小扰动，在Sobolev空间中证明了全局时间解的存在唯一性，方法结合抵消机制与线性良好未知量思想。

Boundary Layer Problems in the Viscosity-Diffusion Vanishing Limits for the Incompressible MHD Systems

In this paper, we we study boundary layer problems for the incompressible MHD systems in the presence of physical boundaries with the standard Dirichlet oundary conditions with small generic viscosity and diffusion coefficients. We identify a non-trivial class of initial data for which we can establish the uniform stability of the Prandtl's type boundary layers and prove rigorously that the solutions to the viscous and diffusive incompressible MHD systems converges strongly to the superposition of the solution to the ideal MHD systems with a Prandtl's type boundary layer corrector. One of the …

MHD boundary layers theory in Sobolev spaces without monotonicity. I. well-posedness theory

We study the well-posedness theory for the MHD boundary layer. The boundary layer equations are governed by the Prandtl type equations that are derived from the incompressible MHD system with non-slip boundary condition on the velocity and perfectly conducting condition on the magnetic field. Under the assumption that the initial tangential magnetic field is not zero, we establish the local-in-time existence, uniqueness of solution for the nonlinear MHD boundary layer equations. Compared with the well-posedness theory of the classical Prandtl equations for which the monotonicity condition of t…

Existence and uniqueness of solution of free boundary problems with partially degenerate diffusion

In this paper, we mainly introduce a general method to study the existence and uniqueness of solution of free boundary problems with partially degenerate diffusion.

无磁扩散的二维不可压缩MHD方程的全局适定性

Global well-posedness of 2D incompressible MHD equations without magnetic diffusion

针对无磁扩散二维不可压缩粘性MHD方程经典解全局存在性的开放问题，本文利用阿尔文波色散效应，通过构造特殊量控制非线性项，证明了H²空间小初始扰动下全局唯一解的存在性。

On the uniqueness of a solution to a stationary convection-diffusion equation with a generalized divergence-free drift

In this paper we establish the uniqueness of a solution to a stationary convection-diffusion equation in divergence form with an exponentially summable generalized divergence-free drift.

Higher order commutator estimates and local existence for the non-resistive MHD equations and related models

This paper establishes the local-in-time existence and uniqueness of strong solutions in $H^{s}$ for $s > n/2$ to the viscous, non-resistive magnetohydrodynamics (MHD) equations in $\mathbb{R}^{n}$, $n=2, 3$, as well as for a related model where the advection terms are removed from the velocity equation. The uniform bounds required for proving existence are established by means of a new estimate, which is a partial generalisation of the commutator estimate of Kato & Ponce (Comm. Pure Appl. Math. 41(7), 891-907, 1988).

The global well-posedness of strong solutions to 2D MHD equations in Lei-Lin space

In this paper, we study the Cauchy problem of the 2D incompressible magnetohydrodynamic equations in Lei-Lin space. The global well-posedness of a strong solution in the Lei-Lin space $χ^{-1}(\mathbb{R}^2)$ with any initial data in $χ^{-1}(\mathbb{R}^2)\cap L^2(\mathbb{R}^2)$ is established. Furthermore, the uniqueness of the strong solution in $χ^{-1}(\mathbb{R}^2)$ and the Leray-Hopf weak solution in $L^2(\mathbb{R}^2)$ is proved.

Global existence and uniqueness for a volume-surface reaction-nonlinear-diffusion system

We prove a global existence, uniqueness and regularity result for a two-species reaction-diffusion volume-surface system that includes nonlinear bulk diffusion and nonlinear (weak) cross diffusion on the active surface. A key feature is a proof of upper $L^{\infty}$-bounds that exploits the entropic gradient structure of the system.

Existence and uniqueness analysis of a non-isothermal cross-diffusion system of Maxwell-Stefan type

In this article we prove local-in-time existence and uniqueness of solution to a non-isothermal cross-diffusion system with Maxwell-Stefan structure.

Uniqueness of the inverse reaction coefficient problems for nonlocal diffusion models

In this paper, we consider the inverse reaction coefficient problems (IRCPs) for nonlocal diffusion equation and multi-term time-fractional nonlocal diffusion equation from the average nonlocal flux data in external reaction region. Based on the nonlocal maximum principle we established, the uniqueness theorem for IRCPs are proved.

Well-posedness in Sobolev spaces of the two-dimensional MHD Boundary layer equations without viscosity

We consider the two-dimensional MHD Boundary layer system without hydrodynamic viscosity, and establish the existence and uniqueness of solutions in Sobolev spaces under the assumption that the tangential component of magnetic fields dominates. This gives a complement to the previous works of Liu-Xie-Yang [Comm. Pure Appl. Math. 72 (2019)] and Liu-Wang-Xie-Yang [J. Funct. Anal. 279 (2020)], where the well-posedness theory was established for the MHD boundary layer systems with both viscosity and resistivity and with viscosity only, respectively. We use the pseudo-differential calculation, to o…

Uniqueness for inverse problems of determining orders of multi-term time-fractional derivatives of diffusion equation

This article proves the uniqueness for two kinds of inverse problems of identifying fractional orders in diffusion equations with multiple time-fractional derivatives by pointwise observation. By means of eigenfunction expansion and Laplace transform, we reduce the uniqueness for our inverse problems to the uniqueness of expansions of some special function and complete the proof.

On the uniqueness of semi-wavefronts for non-local delayed reaction-diffusion equations

We establish the uniqueness of semi-wavefront solution for a non-local delayed reaction-diffusion equation. This result is obtained by using a generalization of the Diekman-Kaper theory for a nonlinear convolution equation. Several applications to the systems of non-local reaction-diffusion equations with distributed time delay are also considered.

Uniqueness in inverse boundary value problems for fractional diffusion equations

We consider an inverse boundary value problem for diffusion equations with multiple fractional time derivatives. We prove the uniqueness in determining a number of fractional time-derivative terms, the orders of the derivatives and spatially varying coefficients.

三维随机磁流体动力学方程概率强解的存在性与非唯一性

Existence and non-uniqueness of probabilistically strong solutions to 3D stochastic magnetohydrodynamic equations

本文针对三维随机MHD方程，在超临界LPS区域构造无穷多个概率强解，证明其非唯一性，并揭示噪声消失时解的聚点包含所有确定性MHD解。