Computer-assisted proof of heteroclinic connections in the one-dimensional Ohta-Kawasaki model

65. Jacek Cyranka, Thomas Wanner:
    Computer-assisted proof of heteroclinic connections in the one-dimensional Ohta-Kawasaki model
    SIAM Journal on Applied Dynamical Systems 17(1), pp. 694-731, 2018.

Abstract

We present a computer-assisted proof of heteroclinic connections in the one-dimensional Ohta-Kawasaki model of diblock copolymers. The model is a fourth-order parabolic partial differential equation subject to homogeneous Neumann boundary conditions, which contains as a special case the celebrated Cahn-Hilliard equation. While the attractor structure of the latter model is completely understood for one-dimensional domains, the diblock copolymer extension exhibits considerably richer long-term dynamical behavior, which includes a high level of multistability. In this paper, we establish the existence of certain heteroclinic connections between the homogeneous equilibrium state and local and global energy minimizers. The proof of the above statement is conceptually simple and combines several techniques from some of the authors' and Zgliczynski’s works. Central for the verification is the rigorous propagation of a piece of the unstable manifold of the homogeneous state with respect to time. This propagation has to lead to small interval bounds, while at the same time entering the basin of attraction of the stable fixed point. For interesting parameter values the global attractor exhibits a complicated equilibrium structure, and the dynamical equation is rather stiff. This leads to a time-consuming numerical propagation of error bounds, with many integration steps. This problem is addressed using an efficient algorithm for the rigorous integration of partial differential equations forward in time. The method is able to handle large integration times within a reasonable computational time frame, and this makes it possible to establish heteroclinic connections at various nontrivial parameter values.

Links

The preprint version of the paper can be downloaded from https://arxiv.org/abs/1703.01022, while the published version of the paper can be found at https://doi.org/10.1137/17M111938X.

Bibtex

@article{cyranka:wanner:18a,
   author = {Jacek Cyranka and Thomas Wanner},
   title = {Computer-assisted proof of heteroclinic connections in the
            one-dimensional {O}hta-{K}awasaki model},
   journal = {SIAM Journal on Applied Dynamical Systems},
   volume = {17},
   number = {1},
   year = {2018},
   pages = {694--731},
   doi = {10.1137/17M111938X}