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arXiv 2009.12959math.AP
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双非线性反应扩散方程的行波性态

Travelling-wave behaviour in doubly nonlinear reaction-diffusion equations

Yihong Du, Alejandro Garriz, Fernando Quiros

摘要:

研究一类反应扩散方程,该方程具有双重非线性特征,由$p$ -Laplacian算子和多孔介质算子的组合给出.我们认为所谓的慢扩散制度,对应于退化的行为在0级,\normalcolor,其中非负的解决方案与companies支持的初始数据有一个紧凑的支持,任何以后的时间。对于某些结果,我们还需要$p\ge2$来避免远离0的奇异行为的可能性。在这个家庭中的问题有一个独特的(平移)行波与有限的前面。当初始数据是有界的,径向对称的和紧支撑的,我们将证明,解决方案收敛到1(存在,如我们所示,为所有的反应项考虑广泛类的初始数据)这样做,通过接近这个独特的行波在径向方向上的平移,但与对数校正的前的位置时,尺寸大于1。作为推论,我们得到的自由边界和水平集在非径向的情况下的误差项的大小$O(1)$的渐近位置。在一维,我们扩展我们的结果,以涵盖的情况下,非对称的初始数据,以及有界的初始数据的情况下,支持集无界的一个方向的真正的线。独立感兴趣的主要技术工具是通量的估计。即使对于多孔介质方程和$p$ -Laplacian发展方程的特殊情况,我们的结果也是新的。

英文摘要:

We study a family of reaction-diffusion equations that present a doubly nonlinear character given by a combination of the $p$-Laplacian and the porous medium operators. We consider the so-called slow diffusion regime, corresponding to a degenerate behaviour at the level 0, \normalcolor in which nonnegative solutions with compactly supported initial data have a compact support for any later time. For some results we will also require $p\ge2$ to avoid the possibility of a singular behaviour away from 0. Problems in this family have a unique (up to translations) travelling wave with a finite front. When the initial datum is bounded, radially symmetric and compactly supported, we will prove that solutions converging to 1 (which exist, as we show, for all the reaction terms under consideration for wide classes of initial data) do so by approaching a translation of this unique traveling wave in the radial direction, but with a logarithmic correction in the position of the front when the dimension is bigger than one. As a corollary we obtain the asymptotic location of the free boundary and level sets in the non-radial case up to an error term of size $O(1)$. In dimension one we extend our results to cover the case of non-symmetric initial data, as well as the case of bounded initial data with supporting sets unbounded in one direction of the real line. A main technical tool of independent interest is an estimate for the flux. Most of our results are new even for the special cases of the porous medium equation and the $p$-Laplacian evolution equation.

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