论文标题

高度旋转流体动力学中的一些稳定性和不稳定性问题

Some stability and instability issues in the dynamics of highly rotating fluids

论文作者

Sbaiz, Gabriele

论文摘要

在本文中,我们对大规模流动动力学的描述感兴趣。在这种情况下,流体由旋转,弱的可压缩性和分层效应控制,其重要性是通过授权数量来衡量的:Rossby,Mach和Froude数字。论文的第一部分致力于对3D多尺度问题进行分析,称为完整的Navier-Stokes-tokes-fourousy系统,其中考虑了密度和温度的变化,此外,我们还考虑了科里奥利,离心力和重力力量。我们在弱解决方案的框架内研究了小马赫,弗洛德和罗斯比数字的政权中不可压缩和快速的旋转限制,以及一般准备不足的初始数据。在MACH号高于Rossby号码的情况下,我们证明了极限动力学是由不可压缩的Oberbeck-BoussinesQ类型系统描述的。相反,当马赫和罗斯比的数量级相同时,我们会显示出倾向于准地藻型方程的融合。在论文的第二部分中,在渐近分析的“ Le Fil Rouge”之后,我们研究了高旋转对2D不可压缩密度依赖性Euler系统的影响。现在,主要目标是在快速旋转方案中执行单一限制,以显示Euler方程与准同质类型系统的收敛性。两个原始问题向简化模型的收敛证明是基于补偿的紧凑性论点。关键点是使用庞加莱波的基础系统的结构,以确定适合数量的一些紧凑特性。与以前的结果相比,我们的方法使您可以在多尺度问题中处理整个参数范围,并且可以达到和超越关键选择$ fr = \ sqrt {ma} $。

In the present thesis, we are interested in the description of the dynamics of flows on large scales. In this context, the fluids are governed by rotational, weak compressibility and stratification effects, whose importance is measured by adimensional numbers: the Rossby, Mach and Froude numbers. The first part of the thesis is dedicated to the analysis of a 3D multi-scale problem called the full Navier-Stokes-Fourier system where variations in density and temperature are considered and in addition we take into account the Coriolis, centrifugal and gravitational forces. We study, in the framework of weak solutions, the combined incompressible and fast rotation limits in the regime of small Mach, Froude and Rossby numbers and for general ill-prepared initial data. In the case when the Mach number is of higher order than the Rossby number, we prove that the limit dynamics is described by an incompressible Oberbeck-Boussinesq type system. Conversely, when the Mach and Rossby numbers have the same order of magnitude, we show convergence towards a quasi-geostrophic type equation. Following "le fil rouge" of the asymptotic analysis, in the second part of the thesis, we examine the effects of high rotation for the 2D incompressible density-dependent Euler system. Now, the main goal is to perform the singular limit in the fast rotation regime, showing the convergence of the Euler equations to a quasi-homogeneous type system. The proof of convergence of the two primitive problems towards the reduced models is based on a compensated compactness argument. The key point is to use the structure of the underlying system of Poincaré waves in order to identify some compactness properties for suitable quantities. Compared to previous results, our method enables to treat the whole range of parameters in the multi-scale problem, and also to reach and go beyond the critical choice $Fr=\sqrt{Ma}$.

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