Solving the regularized, strongly anisotropic Cahn-Hilliard equation by an adaptive nonlinear multigrid method

Steven Wise, Junseok Kim, John Lowengrub

Research output: Contribution to journalArticle

131 Citations (Scopus)

Abstract

We present efficient, second-order accurate and adaptive finite-difference methods to solve the regularized, strongly anisotropic Cahn-Hilliard equation in 2D and 3D. When the surface energy anisotropy is sufficiently strong, there are missing orientations in the equilibrium level curves of the diffuse interface solutions, corresponding to those missing from the sharp interface Wulff shape, and the anisotropic Cahn-Hilliard equation becomes ill-posed. To regularize the equation, a higher-order derivative term is added to the energy. This leads to a sixth-order, nonlinear parabolic equation for the order parameter. An implicit time discretization is used to remove the high-order time step stability constraints. Dynamic block-structured Cartesian mesh refinement is used to highly resolve narrow interfacial layers. A multilevel, nonlinear multigrid method is used to solve the nonlinear equations at the implicit time level. One of the keys to the success of the method is the treatment of the anisotropic term. This term is discretized in conservation form in space and is discretized fully implicitly in time. Numerical simulations are presented that confirm the accuracy, efficiency and stability of the scheme. We study the dynamics of interfaces under strong anisotropy and compare near-equilibrium diffuse interface solutions to the sharp interface Wulff shapes in 2D and 3D. We also simulate large-scale coarsening of a corrugated surface (in 3D) evolving by anisotropic surface diffusion. We show the emergence of long-range order during coarsening and an interesting mechanism of ordered coarsening.

Original languageEnglish
Pages (from-to)414-446
Number of pages33
JournalJournal of Computational Physics
Volume226
Issue number1
DOIs
Publication statusPublished - 2007 Sep 10
Externally publishedYes

Keywords

  • Adaptive mesh refinement
  • Cahn-Hilliard equation
  • Cartesian grid methods
  • Nonlinear multigrid methods
  • Regularization
  • Strong anisotropy

ASJC Scopus subject areas

  • Numerical Analysis
  • Modelling and Simulation
  • Physics and Astronomy (miscellaneous)
  • Physics and Astronomy(all)
  • Computer Science Applications
  • Computational Mathematics
  • Applied Mathematics

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