On the efficiency of explicit and semi-explicit immersed boundary finite element methods for wave propagation problems
Journal:
arXiv
Published Date:
Jan 31, 2025
Abstract
Immersed boundary methods have attracted substantial interest in the last
decades due to their potential for computations involving complex geometries.
Often these cannot be efficiently discretized using boundary-fitted finite
elements. Immersed boundary methods provide a simple and fully automatic
discretization based on Cartesian grids and tailored quadrature schemes that
account for the geometric model. It can thus be described independently of the
grid, e.g., by image data obtained from computed tomography scans. The drawback
of such a discretization lies in the potentially small overlap between certain
elements in the grid and the geometry. These badly cut elements with small
physical support pose a particular challenge for nonlinear and/or dynamic
simulations. In this work, we focus on problems in structural dynamics and
acoustics and concentrate on solving them with explicit time-marching schemes.
In this context, badly cut elements can lead to unfeasibly small critical time
step sizes. We investigate the performance of implicit-explicit time marching
schemes and two stabilization methods developed in previous works as potential
remedies. While these have been studied before with regard to their
effectiveness in increasing the critical time step size, their numerical
efficiency has only been considered in terms of accuracy per degree of freedom.
In this paper, we evaluate the computation time required for a given accuracy,
which depends not only on the number of degrees of freedom but also on the
selected spatial discretization, the sparsity patterns of the system matrices,
and the employed time-marching scheme.
