IMA Journal of Numerical Analysis Advance Access originally published online on May 26, 2008
IMA Journal of Numerical Analysis 2009 29(3):539-572; doi:10.1093/imanum/drn026
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A convergent finite-difference method for a nonlinear variational wave equation

Department of Mathematical Sciences, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway and Centre of Mathematics for Applications, University of Oslo, PO Box 1053, Blindern, NO-0316 Oslo, Norway


Centre of Mathematics for Applications, University of Oslo, PO Box 1053, Blindern, NO-0316 Oslo, Norway
Corresponding author. Email: holden{at}math.ntnu.no
Email: kennethk{at}math.uio.no
Email: nilshr{at}math.uio.no
Received on 20 August 2007. Revised on 29 January 2008.
| Abstract |
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We establish rigorously convergence of a semidiscrete upwind scheme for the nonlinear variational wave equation utt – c(u)(c(u)ux)x = 0 with u|t=0 = u0 and ut|t=0 = v0. Introducing Riemann invariants R = ut + cux and S = ut – cux, the variational wave equation is equivalent to Rt – cRx
(R2 – S2) and St + cSx = –
(R2 – S2) with
= c'/(4c). An upwind scheme is defined for this system. We assume that the speed c is positive, increasing and both c and its derivative are bounded away from zero and that R|t=0, S|t=0
L1(
)
L3(
) are nonpositive. The numerical scheme is illustrated on several examples.
Key Words: variational wave equation; convergence of finite-difference schemes; liquid crystals