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arXiv 1808.05029math.APphysics.flu-dyn
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含真空的可压缩Euler和Navier-Stokes方程斯托克斯方程的能量守恒

Energy Conservation for the Compressible Euler and Navier-Stokes Equations with Vacuum

Ibrokhimbek Akramov, Tomasz Dębiec, Jack W. D. Skipper, Emil Wiedemann

摘要:

考虑具有压力律$p\in C^{1,γ-1}$的$\mathbb{T}^d\times [0,T]$上的可压缩等熵Euler方程,其中$1\le γ<2$ .这包括所有物理相关的情况,例如\单原子气体研究了弱解在什么条件下正则性守恒。以前的结果主要假设$p\in C^2$在密度的范围内,然而,对于现实的压力定律,这意味着我们必须排除真空的情况。在这里,我们通过给出能量守恒的一些充分条件来改进这些结果,甚至对于可能呈现真空的解也是如此:首先,假设速度是一个发散测度场;其次,在真空附近对$1/ρ$施加额外的可积性;第三,假设$ρ$在真空附近是拟近亚谐的;最后,假设$u$和$ρ$是Hölder连续的。然后,我们扩展这些结果,以显示全局能量守恒的域$Ω\times [0,T]$,其中$Ω$是有界的$C^2$边界。我们表明,我们可以推广这些结果的可压缩Navier-斯托克斯方程,甚至与退化的粘度。

英文摘要:

We consider the compressible isentropic Euler equations on $\mathbb{T}^d\times [0,T]$ with a pressure law $p\in C^{1,γ-1}$, where $1\le γ<2$. This includes all physically relevant cases, e.g.\ the monoatomic gas. We investigate under what conditions on its regularity a weak solution conserves the energy. Previous results have crucially assumed that $p\in C^2$ in the range of the density, however, for realistic pressure laws this means that we must exclude the vacuum case. Here we improve these results by giving a number of sufficient conditions for the conservation of energy, even for solutions that may exhibit vacuum: Firstly, by assuming the velocity to be a divergence-measure field; secondly, imposing extra integrability on $1/ρ$ near a vacuum; thirdly, assuming $ρ$ to be quasi-nearly subharmonic near a vacuum; and finally, by assuming that $u$ and $ρ$ are Hölder continuous. We then extend these results to show global energy conservation for the domain $Ω\times [0,T]$ where $Ω$ is bounded with a $C^2$ boundary. We show that we can extend these results to the compressible Navier-Stokes equations, even with degenerate viscosity.

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