A renormalized Newton method for liquid crystal director modeling

Eugene C. Gartland, Jr, Alison Ramage

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7 Citations (Scopus)
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Abstract

We consider the nonlinear systems of equations that result from discretizations of a prototype variational model for the equilibrium director field characterizing the orientational properties of a liquid crystal material. In the presence of pointwise unit-vector constraints and coupled electric fields, the numerical solution of such equations by Lagrange-Newton methods leads to linear systems with a double saddle-point form, for which we have previously proposed a preconditioned nullspace method as an effective solver [A. Ramage and E. C. Gartland, Jr., SIAM J. Sci. Comput., 35 (2013), pp. B226–B247]. Here we propose and analyze a modified outer iteration (“Renormalized Newton Method”) in which the orientation variables are normalized onto the constraint manifold at each iterative step. This scheme takes advantage of the special structure of these problems, and we prove that it is locally quadratically convergent. The Renormalized Newton Method bears some resemblance to the Truncated Newton Method of computational micromagnetics, and we compare and contrast the two. This brings to light some anomalies of the Truncated Newton Method.
Original languageEnglish
Pages (from-to)251-278
Number of pages28
JournalSIAM Journal on Numerical Analysis
Volume53
Issue number1
Early online date22 Jan 2015
DOIs
Publication statusPublished - 2015

Keywords

  • reduced hessian method
  • saddle-point problems
  • unit-vector constraints
  • director models
  • liquid crystals
  • renormalized newton method

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