On Properties of Compact 4th order Finite-Difference Schemes for the Variable Coefficient Wave Equation

Abstract

We consider an initial-boundary value problem for the $n$-dimensional wave equation with the variable sound speed, $n\ge 1$. We construct three-level implicit in time and compact in space (three-point in each space direction) 4th order finite-difference schemes on the uniform rectangular meshes including their one-parameter (for $n=2$) and three-parameter (for $n=3$) families. We also show that some already known methods can be converted into such schemes. In a unified manner, we prove the conditional stability of schemes in the strong and weak energy norms together with the 4th order error estimate under natural conditions on the time step. We also transform an unconditionally stable 4th order two-level scheme suggested for $n=2$ to the three-level form, extend it for any $n\ge 1$ and prove its stability. We also give an example of a compact scheme for non-uniform in space and time rectangular meshes. We suggest simple fast iterative methods based on FFT to implement the schemes. A new effective initial guess to start iterations is given too. We also present promising results of numerical experiments.

25 pages, 2 figures, 7 tables

References in corpus (1)

• On compact 4th order finite-difference schemes for the wave equation

Cited by in corpus (3)

• On properties of an explicit in time fourth-order vector compact scheme for the multidimensional wave equation
• On properties of a semi-explicit in time fourth-order vector compact scheme for the multidimensional acoustic wave equation
• Upper and Lower Error Bounds for a Compact Fourth-Order Finite-Difference Scheme for the Wave Equation with Nonsmooth Data