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arXiv 2407.17439math.AP
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三维等熵可压缩Navier-Stokes方程解的长时间行为

Long-time behavior to the 3D isentropic compressible Navier-Stokes equations

Guochun Wu, Xin Zhong

AI总结:

本文研究三维全空间等熵可压缩Navier-Stokes方程经典解的长时间行为,在更弱假设下得到最优衰减速率,推广真空持久性结论到全空间,首次给出有真空时压力的L^∞衰减速率结果。

摘要:

本文研究$\u211d^3$空间中等熵可压缩Navier-Stokes方程经典解的长时间行为。主要结果与创新点如下:在密度$ρ(\mathbf{x},t)$满足$ρ(\mathbf{x},0)\geq c>0$且$\sup_{t\geq 0}\\|ρ(\cdot,t)\\|_{L^\infty}\leq M$的假设下,我们建立了解的最优衰减速率,这一结果大幅改进了此前的研究(Arch. Ration. Mech. Anal. 234 (2019), 1167--1222),该文献的作者要求额外假设$\sup_{t\geq 0}\\|ρ(\cdot,t)\\|_{C^α}\leq M$,其中$α$为任意小的正数。我们证明,若初始密度包含真空且远场密度远离真空,则真空状态会在任意时刻持续存在,这将SIAM J. Math. Anal. 55 (2023), 882--899中得到的环面情形结论推广到了全空间。我们推导了远场密度为真空的解的衰减性质,其中特别给出了存在真空时三维可压缩Navier-Stokes方程压力以$(1+t)^{-1}$速率进行$L^\infty$衰减的首个结果。证明的核心要素依赖于爆破准则、密度的关键时间无关正上下界以及正则性插值技巧。

英文摘要:

We are concerned with the long-time behavior of classical solutions to the isentropic compressible Navier-Stokes equations in $\mathbb R^3$. Our main results and innovations can be stated as follows: Under the assumption that the density $ρ({\bf{x}}, t)$ verifies $ρ({\bf{x}},0)\geq c>0$ and $\sup_{t\geq 0}\|ρ(\cdot,t)\|_{L^\infty}\leq M$, we establish the optimal decay rates of the solutions. This greatly improves the previous result (Arch. Ration. Mech. Anal. 234 (2019), 1167--1222), where the authors require an extra hypothesis $\sup_{t\geq 0}\|ρ(\cdot,t)\|_{C^α}\leq M$ with $α$ arbitrarily small. We prove that the vacuum state will persist for any time provided that the initial density contains vacuum and the far-field density is away from vacuum, which extends the torus case obtained in (SIAM J. Math. Anal. 55 (2023), 882--899) to the whole space. We derive the decay properties of the solutions with vacuum as far-field density. This in particular gives the first result concerning the $L^\infty$-decay with a rate $(1+t)^{-1}$ for the pressure to the 3D compressible Navier-Stokes equations in the presence of vacuum. The main ingredient of the proof relies on the techniques involving blow-up criterion, a key time-independent positive upper and lower bounds of the density, and a regularity interpolation trick.

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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