A fast linearized finite difference method for the nonlinear multi-term time-fractional wave equation

摘要

In this paper, we study a fast and linearized finite difference method to solve the nonlinear time-fractional wave equation with multi fractional orders. We first propose a discretization to the multi-term Caputo derivative based on the recently established fast L2-1_σ formula and a weighted approach. Then we apply the discretization to construct a fully fast linearized discrete scheme for the nonlinear problem under consideration. The nonlinear term, which just fulfills the Lipschitz condition, will be evaluated on the previous time level. Therefore only linear systems are needed to be solved for obtaining numerical solutions. The proposed scheme is shown to have second-order unconditional convergence with respect to the discrete H~1-norm. The proposed fast linearized method can be directly extended to solve the nonlinear distributed-order time-fractional wave problem. Numerical examples are provided to justify the efficiency.