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arXiv physics/0608096physics.flu-dyn
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三维粘性和无粘性简化Bardina Turbulence模型的整体适定性

Global Well-posedness of the Three-dimensional Viscous and Inviscid Simplified Bardina Turbulence Models

Y. Cao, E. M. Lunasin, E. S. Titi

摘要:

本文对具有周期边界条件的三维粘性和无粘性简化Bardina湍流模型进行了分析研究。粘性模型弱解的整体存在唯一性已经由Layton和Lewandowski建立。然而,我们在这里证明了较弱的初始条件下,该模型的整体适定性。我们还建立了一个上限,其全球吸引子的尺寸,并确定此尺寸的自由度的数量为这个模型。我们表明,自由度的长期动态的解决方案的数量是顺序的$(L/l_d)^{12/5}$,其中$L$是周期盒的大小和$l_d$是耗散长度尺度-相信和定义为最小的长度尺度积极参与的动态流。该上限估计值小于为$(L/l_d)^{3}$阶的Navier-Stokes- $α$、Clark- $α$和Modified-Leray- $α$湍流模型建立的上限估计值。最后,我们建立了无粘模型整体弱解的存在唯一性。这一结果在计算流体动力学中有重要的应用,当无粘简化Bardina模型被认为是三维Euler方程的正则化模型时。

英文摘要:

In this paper we present analytical studies of three-dimensional viscous and inviscid simplified Bardina turbulence models with periodic boundary conditions. The global existence and uniqueness of weak solutions to the viscous model has already been established by Layton and Lewandowski. However, we prove here the global well-posedness of this model for weaker initial conditions. We also establish an upper bound to the dimension of its global attractor and identify this dimension with the number of degrees of freedom for this model. We show that the number of degrees of freedom of the long-time dynamics of the solution is of the order of $(L/l_d)^{12/5}$, where $L$ is the size of the periodic box and $l_d$ is the dissipation length scale-- believed and defined to be the smallest length scale actively participating in the dynamics of the flow. This upper bound estimate is smaller than those established for Navier-Stokes-$α$, Clark-$α$ and Modified-Leray-$α$ turbulence models which are of the order $(L/l_d)^{3}$. Finally, we establish the global existence and uniqueness of weak solutions to the inviscid model. This result has an important application in computational fluid dynamics when the inviscid simplified Bardina model is considered as a regularizing model of the three-dimensional Euler equations.

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