A frequency-dependent p-adaptive technique for spectral methods

When using spectral methods, a consistent method for tuning the expansion order is often required, especially for time-dependent problems in which oscillations emerge in the solution. In this paper, we propose a frequency-dependent p-adaptive technique that adaptively adjusts the expansion order based on a frequency indicator. Using this p-adaptive technique, combined with recently proposed scaling and moving techniques, we are able to devise an adaptive spectral method in unbounded domains that can capture and handle diffusion, advection, and oscillations. As an application, we use this adaptive spectral method to numerically solve Schrodinger's equation in an unbounded domain and successfully capture the solution's oscillatory behavior at infinity. (C) 2021 The Authors. Published by Elsevier Inc.