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arXiv 2005.00651math.AP
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椭圆方程单调前沿的全局分歧

Global bifurcation for monotone fronts of elliptic equations

Robin Ming Chen, Samuel Walsh, Miles H. Wheeler

AI总结:

本文基于Dancer和Buffoni--Toland的解析全局分歧理论,研究无穷圆柱上椭圆方程单调前沿解的全局延拓,并应用于构造二维两相欧拉方程中内部水跃的全局族,首次给出大幅抬升与下降水跃的连续曲线及其极端行为。

摘要:

本文给出了关于无穷圆柱上椭圆偏微分方程单调前沿型解的全局延拓的两个结果。这些结果在相当一般的假设下成立,尤其适用于完全非线性方程以及具有透射边界条件的拟线性问题。我们的方法植根于Dancer和Buffoni--Toland的解析全局分歧理论,但将其推广到无界区域需要处理与紧性丧失相关的新的潜在极限行为。我们获得了解曲线全局行为的穷尽且尖锐的备选集合,其中每种可能性在二阶常微分方程的分歧理论中都有直接类比。作为一般理论的一个主要应用,我们构造了内部水跃的全局族。这些是二维全两相欧拉方程的移动前沿解。流体被限制在上下由刚性壁界定的通道中,每一层中的流动都是不可压缩且无旋的。该系统的小幅前沿已由多位作者获得。我们首次给出了大幅结果,形式为抬升水跃和下降水跃的连续曲线。沿抬升曲线至其极端,我们发现波的界面要么翻转(发展出垂直切线),要么变得异常奇异,即两层中的流动在边界上的单一点处退化。对于下降波曲线,我们证明界面要么翻转,要么与上壁接触。

英文摘要:

In this paper, we present two results on global continuation of monotone front-type solutions to elliptic PDEs posed on infinite cylinders. This is done under quite general assumptions, and in particular applies even to fully nonlinear equations as well as quasilinear problems with transmission boundary conditions. Our approach is rooted in the analytic global bifurcation theory of Dancer and Buffoni--Toland, but extending it to unbounded domains requires contending with new potential limiting behavior relating to loss of compactness. We obtain an exhaustive set of alternatives for the global behavior of the solution curve that is sharp, with each possibility having a direct analogue in the bifurcation theory of second-order ODEs. As a major application of the general theory, we construct global families of internal hydrodynamic bores. These are traveling front solutions of the full two-phase Euler equation in two dimensions. The fluids are confined to a channel that is bounded above and below by rigid walls, with incompressible and irrotational flow in each layer. Small-amplitude fronts for this system have been obtained by several authors. We give the first large-amplitude result in the form of continuous curves of elevation and depression bores. Following the elevation curve to its extreme, we find waves whose interfaces either overturn (develop a vertical tangent) or become exceptionally singular in that the flow in both layers degenerates at a single point on the boundary. For the curve of depression waves, we prove that either the interface overturns or it comes into contact with the upper wall.

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