A New Multi-Symplectic Scheme for the KdV Equation

We propose a new multi-symplectic integrating scheme for the Korteweg-de Vries (KdV) equation. The new scheme is derived by concatenating spatial discretization of the multi-symplectic Fourier pseudospectral method with temporal discretization of the symplectic Euler scheme. The new scheme is explicit in the sense that it does not need to solve nonlinear algebraic equations. It is verified that the multi-symplectic semi-discretization of the KdV equation under periodic boundary conditions has N semi-discrete multi-symplectic conservation laws. We also prove that the full-discrete scheme has N full-discrete multi-symplectic conservation laws. Numerical experiments of the new scheme on the KdV equation are made to demonstrate the stability and other merits for long-time integration.