A numerically efficient and conservative model for a Riesz space-fractional Klein–Gordon–Zakharov system.

Highlights • The existence of invariants for a fractional Klein–Gordon–Zakharov equation is established. • A second-order numerical model is proposed to solve the continuous model. • The model has discrete forms of the invariants which are also conserved. • The existence, uniqueness and boundedness of the numerical solutions are proved. • We prove stability and convergence using a form of the discrete energy method. Abstract Departing from a fractional extension of the well-known one-dimensional Klein–Gordon–Zakharov system, we propose a numerically efficient model to approximate its solutions. The continuous model under investigation considers fractional derivatives of the Riesz type in space, with orders of differentiation in (1, 2]. In analogy with the non-fractional regime, the existence of a positive conserved energy quantity is established in this work. Motivated by this fact, the design of the numerical model focuses on the preservation of the energy. Using fractional-order centered differences to approximate the fractional partial derivatives, we propose a numerical model that preserves a positive discrete form of the energy. The existence and uniqueness of solutions are thoroughly established using fixed-point arguments, and the usual argument with Taylor polynomials is employed to prove the consistency of the numerical model. Some suitable bounds in terms of the energy invariants are found for the solutions of the numerical model. Moreover, using an extension of the energy method for fractional systems, we establish the stability and the convergence properties of the methodology. Finally, we provide some examples to illustrate the accuracy of our numerical implementation, including a numerical study of the convergence rate of the scheme that confirms the validity of the analytical results derived in this work. [ABSTRACT FROM AUTHOR]