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arXiv 1806.09799math.AP
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具有物理真空的非等熵Euler方程的适定性

Well-posedness of nonisentropic Euler equations with physical vacuum

Yongcai Geng, Yachun Li, Dehua Wang, Runzhang Xu

摘要:

考虑了一维非等熵Euler方程在运动物理真空边界条件下的局部适定性。物理真空奇异性要求将声速换算为到真空边界的距离的平方根。主要困难在于双曲守恒律系统在真空边界处变得特征化和退化。我们的证明是基于近似的欧拉方程的退化抛物正则化从一个特定的选择退化的人工粘性项。然后我们构造了这个退化抛物问题的解,并建立了关于人工粘性参数的一致估计。可压缩欧拉方程的解作为消失的人工粘性的极限而得到。与等熵情形\cite{Coutand4, Lei}不同的是,我们的守恒律动量方程中多了一项$p_{S}S_x$,这导致了能量函数中的一些额外项,甚至对$γ=2$情形也造成了更大的困难.此外,我们从$2\leqγ<3$和$1<γ<2 $的一般情况出发处理这个自由边界问题,而不是只强调\cite{Coutand4, jang1, Lei}中$γ=2$的等熵情况。

英文摘要:

We consider the local well-posedness of the one-dimensional nonisentropic Euler equations with moving physical vacuum boundary condition. The physical vacuum singularity requires the sound speed to be scaled as the square root of the distance to the vacuum boundary. The main difficulty lies in the fact that the system of hyperbolic conservation laws becomes characteristic and degenerate at the vacuum boundary. Our proof is based on an approximation of the Euler equations by a degenerate parabolic regularization obtained from a specific choice of a degenerate artificial viscosity term. Then we construct the solutions to this degenerate parabolic problem and establish the estimates that are uniform with respect to the artificial viscosity parameter. Solutions to the compressible Euler equations are obtained as the limit of the vanishing artificial viscosity. Different from the isentropic case \cite{Coutand4, Lei}, our momentum equation of conservation laws has an extra term $p_{S}S_x$ that leads to some extra terms in the energy function and causes more difficulties even for the case of $γ=2$. Moreover, we deal with this free boundary problem starting from the general cases of $2\leqγ<3$ and $1<γ<2 $ instead of only emphasizing the isentropic case of $γ=2$ in \cite{Coutand4, jang1, Lei}.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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