Galerkin finite element methods for the numerical solution of two classical-Boussinesq type systems over variable bottom topography

TL;DR

This paper develops and analyzes Galerkin finite element methods for two Boussinesq-type systems modeling long surface waves over variable bottoms, providing error estimates and numerical simulations validated against experimental data.

Contribution

It introduces spatial discretization and error analysis for two Boussinesq systems over variable bottoms, including implementation with Runge-Kutta time-stepping and comparison with experimental results.

Findings

Both systems accurately model solitary wave evolution over variable bottoms.

The numerical schemes effectively capture dispersive wave phenomena.

Simulations align well with experimental data from literature.

Abstract

We consider two `Classical' Boussinesq type systems modelling two-way propagation of long surface waves in a finite channel with variable bottom topography. Both systems are derived from the 1-d Serre-Green-Naghdi (SGN) system; one of them is valid for stronger bottom variations, and coincides with Peregrine's system, and the other is valid for smaller bottom variations. We discretize in the spatial variable simple initial-boundary-value problems (ibvp's) for both systems using standard Galerkin-finite element methods and prove $L^2$ error estimates for the ensuing semidiscrete approximations. We couple the schemes with the 4th order-accurate, explicit, classical Runge-Kutta time-stepping procedure and use the resulting fully discrete methods in numerical simulations of dispersive wave propagation over variable bottoms with several kinds of boundary conditions, including absorbing ones. We describe in detail the changes that solitary waves undergo when evolving under each system over a variety of variable-bottom environments. We assess the efficacy of both systems in approximating these flows by comparing the results of their simulations with each other, with simulations of the SGN-system, and with available experimental data from the literature.