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arXiv 1305.2185math.AP
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遍历代数中退化多孔介质型方程的均匀化

Homogenization of Degenerate Porous Medium Type Equations in Ergodic Algebras

Hermano Frid, Jean Silva

摘要:

考虑了一般多孔介质型方程$u_t=\D f(x,\frac{x}{\ve}, u)$的均匀化问题。压力函数$f(x,y,\cdot)$可以是两种不同的类型。在类型1的情况下,$f(x,y,\cdot)$是一般的严格递增函数,这是一个轻度退化的情况。在第2类情况下,$f(x,y,\cdot)$的形式为$h(x,y)F(u)+S(x,y)$,其中$F(u)$只是一个非减函数;这是一种强退化情况。我们解决的初边值问题的一般,有界或无界,域$\Om$,与零(或更一般地说,稳定)的压力条件的边界。均匀化是在遍历代数的一般上下文中进行的。据作者所知,这类退化拟线性抛物型方程的均匀化是第一次讨论。我们还回顾了这类方程的存在性和稳定性理论,并建立了均匀化分析所需的新结果。此外,我们还得到了关于均值代数的一些新结果,特别是一个关于均值代数元素水平集的零测度的新判据,它对于多孔介质型方程在第2类情况下的均匀化是有用的.

英文摘要:

We consider the homogenization problem for general porous medium type equations of the form $u_t=\D f(x,\frac{x}{\ve}, u)$. The pressure function $f(x,y,\cdot)$ may be of two different types. In the type~1 case, $f(x,y,\cdot)$ is a general strictly increasing function; this is a mildly degenerate case. In the type~2 case, $f(x,y,\cdot)$ has the form $h(x,y)F(u)+S(x,y)$, where $F(u)$ is just a nondecreasing function; this is a strongly degenerate case. We address the initial-boundary value problem for a general, bounded or unbounded, domain $\Om$, with null (or, more generally, steady) pressure condition on the boundary. The homogenization is carried out in the general context of ergodic algebras. As far as the authors know, homogenization of such degenerate quasilinear parabolic equations is addressed here for the first time. We also review the existence and stability theory for such equations and establish new results needed for the homogenization analysis. Further, we include some new results on algebras with mean value, specially a new criterion establishing the null measure of level sets of elements of the algebra, which is useful in connection with the homogenization of porous medium type equations in the type~2 case.

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