Padded continued fraction absorbing boundary conditions for dispersive waves

Continued fraction absorbing boundary conditions (CFABCs) are new arbitrarily high-order local absorbing boundary conditions that are highly effective in simulating wave propagation in unbounded domains. The current versions of CFABCs are developed for the non-dispersive acoustic wave equation with convex polygonal computational domains. In this paper, the CFABCs are modified through augmentation of special padding elements, and are effective for absorbing evanescent waves occurring in dispersive wave problems while retaining their absorption properties for propagating waves. The padded CFABCs for dispersive wave equations result in fourth order evolution equations, which are solved using an efficient combination of Crank Nicholson method, Newmark time-stepping scheme, and operator splitting ideas. The effectiveness of the padded CFABCs and their implementation is illustrated through numerical examples with varying levels of dispersion.