Singular Limits for Reaction-Diffusion Equations with Fractional Laplacian and Local or Nonlocal Nonlinearity
Singular Limits for Reaction-Diffusion Equations with Fractional Laplacian and Local or Nonlocal Nonlinearity
复制标题
具有分数拉普拉斯和局部或非局部非线性的反应扩散方程的奇异极限
DOI：
10.1080/03605302.2014.963606
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发表时间：
2014
影响因子：
1.9
通讯作者：
S. Mirrahimi
中科院分区：
文献类型：
--
作者：
S. M'el'eard;S. Mirrahimi
我们进行了一个渐进的分析模型的人口动力学与分数拉普拉斯算子和本地或非本地的反应条款。第一部分研究分数阶Fisher-KPP方程的长时间/长范围重标度问题。这种重新缩放是基于种群的指数传播速度。特别是，我们表明，分数拉普拉斯算子在确定这个速度的唯一作用是在初始层，它确定的解决方案的尾部的厚度。接下来，我们证明了这种重新标度也是可能的模型与非局部反应条款，选择突变模型。然而，为了获得第二种情况下更相关的定性行为，我们在本文的第二部分中引入了第二次重新缩放，其中我们假设扩散步骤很小。这样，我们使用WKB的Answer，得到一个Hamilton-Jacobi方程的极限描述的渐近动力学的解决方案，类似的情况下，选择突变模型与经典的拉普拉斯项或积分核薄尾巴。然而，这里引入的重新缩放与后一种情况非常不同。我们将这些结果推广到多维的情况。
We perform an asymptotic analysis of models of population dynamics with a fractional Laplacian and local or nonlocal reaction terms. The first part of the paper is devoted to the long time/long range rescaling of the fractional Fisher-KPP equation. This rescaling is based on the exponential speed of propagation of the population. In particular we show that the only role of the fractional Laplacian in determining this speed is at the initial layer where it determines the thickness of the tails of the solutions. Next, we show that such rescaling is also possible for models with non-local reaction terms, as selection-mutation models. However, to obtain a more relevant qualitative behavior for this second case, we introduce, in the second part of the paper, a second rescaling where we assume that the diffusion steps are small. In this way, using a WKB ansatz, we obtain a Hamilton-Jacobi equation in the limit which describes the asymptotic dynamics of the solutions, similarly to the case of selection-mutation models with a classical Laplace term or an integral kernel with thin tails. However, the rescaling introduced here is very different from the latter cases. We extend these results to the multidimensional case.