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arXiv 1909.02550math.APmath-phmath.MP
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$3D$可压缩涡欧拉流中的粗糙声波

Rough sound waves in $3D$ compressible Euler flow with vorticity

Marcelo M. Disconzi, Chenyun Luo, Giusy Mazzone, Jared Speck

摘要:

我们证明了一系列的结果绑的规则性和几何解的$3D$可压缩欧拉方程的涡和熵。我们的框架利用并揭示了最近新制定的方程,它分解成一个几何的“(声音)波的一部分”耦合到一个“运输-div-卷曲的一部分”(运输部分简称),这两个部分表现出显着的性能的额外的优点。我们的主要结果是,存在的时间可以控制的$H^{2^+}(\mathbb{R}^3)$ -范数的波部分的初始数据和各种Sobolev和Hölder范数的初始数据的传输部分,后者包括初始涡度和熵。波部分正则性假设在索伯列夫空间的尺度上是最优的:如果只假设初始数据的波部分的$H^2(\mathbb{R}^3)$ -范数的界,冲击就可以立即形成。我们的证明依赖于这样的假设,即初始数据的传输部分比波部分更规则,我们表明,额外的规律性传播的流,即使传输部分的流是深耦合到粗糙的波部分。为了实现我们的方法,我们得到了几个独立的兴趣结果:i)声学几何形状的尖锐估计,即,声锥的几何形状; ii)耦合到涡度和熵的准线性声波的Schauder估计;和iii)运输-div-curl-部分的Schauder估计。与以前的低正则性工作相比,本文的主要新特点是所研究的准线性PDE系统表现出多种传播速度,并且需要对流体的各种组分进行椭圆估计,以避免正则性损失并获得时空可积性。

英文摘要:

We prove a series of results tied to the regularity and geometry of solutions to the $3D$ compressible Euler equations with vorticity and entropy. Our framework exploits and reveals additional virtues of a recent new formulation of the equations, which decomposed the flow into a geometric "(sound) wave-part" coupled to a "transport-div-curl-part" (transport-part for short), with both parts exhibiting remarkable properties. Our main result is that the time of existence can be controlled in terms of the $H^{2^+}(\mathbb{R}^3)$-norm of the wave-part of the initial data and various Sobolev and Hölder norms of the transport-part of the initial data, the latter comprising the initial vorticity and entropy. The wave-part regularity assumptions are optimal in the scale of Sobolev spaces: shocks can instantly form if one only assumes a bound for the $H^2(\mathbb{R}^3)$-norm of the wave-part of the initial data. Our proof relies on the assumption that the transport-part of the initial data is more regular than the wave-part, and we show that the additional regularity is propagated by the flow, even though the transport-part of the flow is deeply coupled to the rougher wave-part. To implement our approach, we derive several results of independent interest: i) sharp estimates for the acoustic geometry, i.e., the geometry of sound cones; ii) Strichartz estimates for quasilinear sound waves coupled to vorticity and entropy; and iii) Schauder estimates for the transport-div-curl-part. Compared to previous works on low regularity, the main new features of the paper are that the quasilinear PDE systems under study exhibit multiple speeds of propagation and that elliptic estimates for various components of the fluid are needed, both to avoid loss of regularity and to gain space-time integrability.

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