Abstract
We consider the discretization problem for U(1)-invariant nonlinear wave equations in any dimension. We show that the classical finite-difference scheme used by Strauss and Vazquez (in J. Comput. Phys. 28, 271–278 (1978)) conserves the positive-definite discrete analog of the energy if the grid ratio satisfies \(dt/dx \leqslant 1/\sqrt n \), where dt and dx are the mesh sizes of the time and space variables and n is the spatial dimension. We also show that, if the grid ratio is \(dt/dx \leqslant 1/\sqrt n \), then there is a discrete analog of charge, and this discrete analog is conserved.
We prove the existence and uniqueness of solutions to the discrete Cauchy problem. We use energy conservation to obtain a priori bounds for finite energy solutions, thus showing that the Strauss-Vazquez finite-difference scheme for the nonlinear Klein-Gordon equation with positive nonlinear term in the Hamiltonian is conditionally stable.
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Supported in part by Alexander von Humboldt Research Award (2006) and by FWF, DFG, and RFBR grants.
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Comech, A., Komech, A. Well-posedness and the energy and charge conservation for nonlinear wave equations in discrete space-time. Russ. J. Math. Phys. 18, 410–419 (2011). https://doi.org/10.1134/S1061920811040030
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DOI: https://doi.org/10.1134/S1061920811040030